The good news is that it lives again, possibly more through luck than skill on my part.
The embarrassing bit next; as mentioned previously, along with leaky PSU capacitors, I'd a couple of dead transistors, one of which was a BC107b.
No problem, 5 ordered off ebay, which came in a TO92 package rather than the normal tin can. But which way are the pin-outs?
My databooks claim BC107/TO92 are L74, i.e. with the flat at the top CBE, left to right.
These aren't, they seem to be L14, like the 2n5551's I ordered. i.e. EBC
When you insert the transistor the right way round, the +95v mysteriously drops to +62V and the intensity control behaves as it should.
Previously I'd phoned a friend for advice, before I first posted on here, he gave me his old Philips PM3055 to help me fault the D755.
John's also ex-GPO/BT, but he used to work in the Area Repair Centre, so was more used to faulting at component level. He couldn't really help with this one though, as even they farmed out 'scope repairs elsewhere.
Guess what, no trace on power-up from the Philips; ho hum, the next project for the clean workshop.
I know the power switch won't latch, but I've located a spare for that, so I can replace it if I get the rest of the 'scope working.
The attached .jpg shows the D755 in action; Trace 1, the sine wave's from an old Heathkit sig. gen. and trace 2, square wave is from the cal. o/p on the scope itself.
It is more focussed in reality, than it seems in the photo.
Many thanks to all
Bill
p.s. Does anyone know of a source for the crumbling clear plastic knob on the time/division dial?