Re: RCA AR88D Comms Receiver.
As built, all valves have decent quality ceramic IO sockets, so these should be OK, though there could always be a contact problem- but substituting the 6J5 several times should have cleaned the mating faces up assuming that the tangs haven't become so fatigued as to engender a problem that way!
The oscillator coil formers for the HF bands are of the-then new-fangled and low-loss polystyrene, with windings held in place by spiral grooves, so no need for wax on these, though the many turns of fine wire for the LF band coils do have a waxy coating. The polystyrene formers can go cloudy-looking though- perhaps micro-cracking which could be hygroscopic. Ceramic is also used for other components such as the bandswitch wafers and gang capacitor insulators, so they should be pretty blameless.
There is some black sleeving over much of the interlinking wiring around the switch wafers which could conceivably have deteriorated and gone leaky if in contact with chassis or metallic things- I had an intermittent ticking as a result of HT leakage to IF bandwidth switch screen because of this in an AR88.
All a bit of a puzzle, really- given the quality of most components in this area, it's one of those sets that should just run and run. Whilst the pink lozenge low-value caps can certainly be suspect, it sounds as though these have been changed. Keep us informed, there are probably a few AR88 owners both intrigued and concerned!
Colin
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