[Arran]

Going to replace caps and resistors and then use isolation xformer to check
B+'s before I start popping tubes into place.

Was thinking about using mild solution to remove oxidization from the tuner cap
and then lubing it with a silicon-based lubricant (tuner cleaner).

I would just stick to regular or lithium grease in the luning condenser bearings, I know they push that silicone junk everywhere now but it often causes as many problems as it solves, tuner bath or soap and water will work to clean it, I use a TSP solution but I'm not going to suggest that . To test the B+ you will need to put the 117Z3 rectifier tube in place, also make sure the set is off before inatlling the battery tubes or they may be blown.
Regards
Arran