Avo valve tester rotary switches

[Kalee20]

       Re the AVO thumbwheel assembly - as Denis said, do not lubricate with hydrocarbon based oils or sprays. When I used to service/repair  RAF CT160's (as Denis did back in the 50's) in the 60's we used a silicone based lubricant - made by Dow Corning, I think. Another "Do Not" is - do not try & prise apart the individual thumbwheels whilst still in-situ in any of the AVO's range of VCM's. Carefully note the colour-coding of the wiring connections, or fit temp. id  sleeving, then de-solder & remove the whole assembly. Note - the top plate can be brittle - take care.

Thanks for these tips, Dave!