EKCO A23 complete restoration needed.

[sobell1980]

Hi all.
I know it's been a while since I've posted on here. But, this hasn't meant I've not been busy in the world of wireless. I've had a repair on a HMV 653 BROADCASTER, that's now gone back to sing happily in its home once more. I'm in the middle of KB10 toaster radio which I'm really enjoying, a lovely set to work on. And, this . A chap I work with approached me and was told I'm the radio man to speak to. The EKCO A23 has been in his family since new. It was his Grandfathers, then his mother's and his mother has asked my work colleague, her son to see it working again. I've taken it on, it's in a bad, bad way. It's been kept in a shed, it will need a total rewire. Not dissimilar to the long 12 month overhaul I did on the HMV 653 which many of you were involved with. I've removed the back, I've hoovered it out and then attempted to remove the 4 knobs with grub screws. There are no heads left on the screws from corrosion and I imagine even if I could remove the screws the knobs would be seized to their respective shafts. I've tried a piece of wire wrapped around behind the knobs with a soft cloth as cushioning incase the screws had just crumbled. I've tried WD40. I fear I'm going to chip, damage and destroy the knobs. I can only see to drill them out carefully. This is very dicey with a drill chuck running so close to the front of the set. Does any one have any bright ideas? Overcome this type of situation before?
Many thanks
Dave.

[Tractionist]

Catswhisker uses some kind of acid .... check his threads. (I've no need to tell you that those particular knobs are quite valuable and went on certain circular Ekcos etc. etc.)

Failing that .... call 'Nick The Dentist' [...... and his drill] !!

Best of luck.

[MurphyNut]

I have one of these and they are lovely radios that sound very good. They're not rare sets perhaps a cheap second set could be found for parts.
Referring to the previous post, I don't think the knobs on the A23 are the same used on the round A22, I seem to remember someone telling me they were in fact a different size.

[slidertogrid]

I had a struggle with a Pye valve tuner with a similar problem. In my case the knobs had two grub screws each. One would not release no matter what I tried.
I tried soaking it with release agent, heating the grub screws with a soldering iron. getting a screwdriver end with a hex and putting a spanner on the hex to really get some leverage but one screw just would not shift.
There was no room to get a drill into the grub screw.

Luckily the knobs had brass effect centre trims. I removed the trim and drilled the centre boss of the knob between the potentiometer spindle and the grub screw in the end I managed to wriggle the knob off.

Some slight damage to the pot spindle but as the knob had two screws it didn't matter once the old screws were drilled out and replaced I managed to refit the knob and the hole I drilled was hidden behind the knob centre trim.

You cannot do the same with these knobs of course as there is no trim to hide the holes.

I would try to get a set of replacements first and then drill the knobs to release them if all else fails...

Rich.

[Boater Sam]

Rich has mentioned most of the ideas I have used.
A piece of steel rod, heated red hot and held on the screw?
Phosphoric acid?
Drill tiny hole in the centre of the knob and inject Plus-Gas, allow to soak. Or acid.
Last resort as mentioned, 3mm drill from the front down between the spindle and the boss where the screw is. The groove thus formed will allow the screw to slide off the spindle. Fill the hole and paint to hide.
Sometimes it just takes time for the acid or release fluid to get to work.
WD40 is a waste of time, Plus-Gas is much better.

[cathoderay57]

You will almost certainly have to resort to drilling. You might want to try a Dremel with a very narrow drill bit. You can sometimes get Dremel bargains at Screwfix. The advantage of the Dremel is it should be small enough to hold in place in front of the face of the radio without damaging it. Even then, the grub screw will be tougher metal than the brass insert (if there is one) or the bakelite/plastic moulding if there isn't. So the drill will probably slip off and widen the grubscrew hole but if done carefully it should enable you to loosen the grubscrew sufficiently to release the knob. Then it's a case of drilling another grubscrew hole somewhere else on the periphery of the knob and cutting a thread in the new hole or using a self-tapping screw to refit the knob. Good luck and keep the swear box open. Cheers, Jerry

[Cobaltblue]

If it all goes horribly wrong please let me know I think I still have the knobs from a terminaly wormed A28 I scrapped more than 20 years ago.

They will take some finding though

Cheers

Mike T

[Andrewausfa]

A better drill would be a COMO or Minicraft, something with a speed controller you can take down to very few rpm. I always find with Dremels, used for precision drilling, they whizz round so fast the damage is done before you can say 'Ooops...'

Andrew

[David G4EBT]

I suspect that by using WD40, you've probably stopped proper penetrating oil such as Plus Gas from being able to enter the threads.

There's only one way I know to stand a good chance of drilling out stuck grub screws and that's to make a drill bit guide which will ensure that a pilot hole can be drilled into the grub screw absolutely centrally so that subsequently larger bits can be used to open up the hole. Any attempt to try to drill a hole centrally in the grub screw without such a guide will end in failure and trash any chance of success.

In the case of the A23 (A22 etc) the clearance hole in the Bakelite knob down which the grub screw passes is 1/4" (6.4mm). If a piece of 1/4" diameter steel rod 1" long is drilled 1/16" diameter, (on a lathe - not in a pillar drill!), and that guide is pushed into the grub screw hole in the knob, a 1/16" bit in a Dremel type drill can then be pushed into the guide to drill a pilot hole in the stuck screw. Ideally, another guide with 1/8" hole should be used to open up the 1/16" hole, then finally, 9/64" which is the tapping size for the 1/4" BSF grub screw, so will have remove all of the remnants of the old screw and will enable the knob to be freed.

I did this successfully on an A22 that I restored for my son some years ago on which all three knobs were stuck, and have successfully removed knobs on other sets this way.

I've attached a rough sketch to show what I mean.

I mention 'Dreme'l, but really, most Dremels and their clones run at a minimum of 10,000 RPM and as has been pointed out, that's rather too high a speed for this sort of task. (I have a Dremel 4000, which goes down to 5,000 RPM). The main thing is to have a guide to ensure a perfectly concentric hole in the old screw.

When replacing the 3/16" BSF grub screws, it makes more sense to use Allen-headed ones rather than slotted, and to save you trying to find them, (long since obsolete of course), there are some here. A little too long, but they can be shortened as desired:

https://www.ebay.co.uk/itm/3-16-Whit...Y1L1RG7HPw9OPw

Every success in your efforts Dave.

[ajgriff]

Really good advice from David. However, if you don't have easy access to a lathe steel capillary tubing is a viable alternative for making suitable guides. This is available in various sizes and short lengths. An eBay search should reveal something suitable at reasonable cost.

Alan

[ajgriff]

One further thought - a flexible drive fitted to a conventional drill might be small enough to do the job whilst allowing better speed control than a dremel.

Alan

[Lloyd 1985]

If you do break either of the 2 larger knobs, I have a couple that someone sent me for my A23 many years ago! He told me that 2 of the knobs were wrong on my set that I’d just bought from the NVCF, and that he’d send me some correct ones, only thing was he sent me 2 of the larger ones, when in fact it was the 2 smaller ones that were wrong! Never mind, it was a very kind and thoughtful gesture, and I’d be happy to pass them on if needed. I’ll have a dig about and see if I can find them.

I’m sure I’ve seen flexible drive shafts for Dremmel type drills before, and the end is nice and small, but it might also work with a bog standard drill too. If using a flexible drive shaft you would probably want it in a bench drill on slow speed rather than a hand held drill, that way you keep a hand free.

Is it possible to loosen the chassis and push it forward a bit to give a bit more room to work? Might also be an idea to tape some thick card or other solid material onto the cabinet whilst working on it so you can’t accidentally gouge it if you slip with the drill!

Regards
Lloyd

[sobell1980]

Wow, thank you all so much for all your very informative and helpful replies. Unfortuneately I don't have access to any machining tools as such. Just a standard hand drill. That will never drill it centre. Love the idea of a drill guide. I think the only way I can do this by myself with what I have is to sadly break apart the knobs and source some more from another donor set. If Mike T and Lloyd could kindly come up with a set between them I would be entirely grateful to the members and this forum once again. Really appreciated everyone's input so far. Loom forwards to replies.
Many thanks.
Dave.

[ms660]

Next best thing to making a drill guide might be a self centering bit provided you can hold the drill to the perpendicular as it were and take it easy, self centering bits are not expensive, also if you have to fit hinges to wood accurately they are a must.

Good luck whichever way.

Lawrence.

Left hand drills are very good for this kind of thing, slow speed and plenty of “push”, they often screw out.

[sobell1980]

Ah ha. I have some left / anti clockwise cut drill bits . They are cobalt Snap On ones. I use them on our classic Jags at work as bolt extractors. Hope I have one small enough.