[CambridgeWorks]

Had this about 5 to 7 years and always been ok. Occasionally, if tilted down or sideways (like you sometimes have to do near a windowsill) you could hear that there was water got into the fan blade and sometimes a bit of spray from the air outlet slots. I never thought this was a good thing and yesterday, it would not power on at all despite a full charge.
I decided to carefully take it apart after trying "banging" it near the switch, which was one google result!
I used an old bath towel on the kitchen table so as to stop things sliding about. This was because my workshop is in need of a blitz as there is just a few square inches of bench space left on my tiny workbench!
The screws looked as if they had ominous non standard torx like heads. However, a small flat blade fitted across 2 slightly larger slots of the six provided, a little like torx, but not the same. Never seen these before.
I found that the pcb component side (SMD ics etc) had some green furry corrosion all around one 8 pin chip. I first un-soldered the 3,6V lithium battery wires from pcb then cleaned up the affected area with ipa and a toothbrush. I also soldered a "u" wire link through two vias, one of which was black with corrosion.
Cautiously, I wired to my bench psu set at 3.7V. It ran at about the correct speed for less than a second, then stopped. It was drawing 4A. I tried slightly different voltages, still the same results.
So, I then reconnected the battery as a last resort and it worked correctly.
I can only assume it didn't like the 5 -6A max of my bench psu?
I then sprayed both sides of the pcb several times with some RS Conformal coating that I have had about 15 or so years. Allowing to dry between each coat. I always knew It would have a use....one day!
I applied fresh grease (multi purpose lithium based car grease) where the original was, as it is used for waterproofing the compartment seals around the motor and pcb part. I had taken several pictures earlier as it looked quite confined inside. Well worth it I found.
Whilst apart, I also dismantled all the suction blade and inlet assembly and cleaned it out. One tip I recommend when re-assembling is to apply a small amount of grease to the self tapping screw threads as it makes re-insertion into the plastic and tightening much easier, bearing in mind the non-standard screwdriver I used to rotate them.
Most difficult part was routing the switch wires upon re-assembly.
So, I saved around £45-£50 cost for a new current model.
Rob