[Drake] ceramic trimmer capacitors

[Darryl Trump]

I think I am having trouble with the crystal trimmer capacitor for the 
LO crystal oscillators in two of my three Drake rigs.  I'm talking 
about the little white ceramic button about 5/8" in diameter that 
sticks up through the chassis and is adjustable.  I think mine may be 
making intermitant connection, drifting, microphonic, and otherwise 
problematic.

Question:  Is this a common problem with sets of this age that use this 
type of capacitor?

Is there a fix other than replacement?  Can you clean and/or lubricate 
these things, and if so, does anybody have a favorite technique?  I 
have cleaned and lubricated many a wafer switch or potentiometer, but 
never tangled with these trimmers before.

Thanks,

KB8BKU, Darryl