PV1 pots/knobs won't turn stuck

[Tzed250]

Hello all,
Three of the six knobs on my PV1 (that's been sitting probably since the 1980s) won't turn at all.
I've tried DeoxIt D5, and a plastic-safe electric motor cleaner but no luck.

It's the three on the left, the input selector, tape monitor, and stereo/mono; all of which are complex 2 or 3 layer affairs.

Did they use some kind of grease from the factory that's now hardened?
Should I try some heat next?

As you know the shafts are round and the knobs only held on by a set-screw, so I'm afraid to apply too much torque that way.
I suppose I could grind some little flats for the set screws so they can't spin as easily?

Thanks in advance for any and all suggestions tips and tricks!

- David

[admin]

Wow, those have been sitting for awhile. I'm guessing the corrosion is extreme or maybe the lube has completely dried and that is what is causing them to be "stuck."

Can they be taken apart to expose the internals? You can try to use some isopropyl alcohol (try to get the pure one, not the typical 70%/30% water mix as you typically don't want water on the electronics) as it may help dislodge dried lubricant.

I don't think heating is going to be the answer. I've never heard people suggesting heating a stuck pot.

Also, if you do get it working again, you will have to relube it most likely.

[Tzed250]

It doesn't appear at first glance that they come apart but I'll take a closer look.
Might be worth a try just removing the lock nut from the front of the panel, pushing them inside the case to see if I can get them into some kind little container in order to really immerse them for a few days. Replacing them obviously a bit of a nightmare LOL

I've used heat to soften/melt old grease before but in mechanical situations not electrical... these are however mechanical in a sense though?
What was the original lubricant, and what do I use now assuming I can get them turning again?

[admin]

I would use something like this for lubrication of the pot after cleaning:

https://www.amazon.com/DeoxIT-Fader-Spr ... 347&sr=8-2