"** By "contacts" you mean the bronze bearings and fingers that ground the moving plates ? "

Exactly. If the plates are clean that is all it needs and usually the alignment stays put enough that you only have to hit the trimmer caps a little bit to tweak it.

And realizing that when you clean a pot you are cleaning the contact to the wiper which is in the center, not the carbon element, I have successfully use LPS2 from the front. It gets through and takes care of it.

It is surprising how long it took for these tuning caps to become in need of cleaning. Back in the 1970s it was unheard of. Even now, alot of people who still have analog tuners just leave them on one station so they never move. Pots also, move them around all the time and they clean themselves.

Of course eventually there will be no such things, just buttons. Oh and rotary encoders. I have a bad problem with those but I am not going to ask you because you are in bumfukt Egypt or whatever. I need to source them here and not for twenty bucks apiece. They are not optical either. And I am serious unsure of how any I will need. I got 53 units and figure by cannibalisation probably get 35 or so of them up and saleable. These things, when the rotary encoder starts going the SOB will go down when you turn it up, up when you turn it down. That can be annoying and I don't want to see these things coming back with bullet holes in them.