One drop of whatever light oil is in reach. Sewing machine usually. I have a bottle on the bench.

+1... Singer sewing machine oil...One drop of whatever light oil is in reach. Sewing machine usually. I have a bottle on the bench.
If one doesn`t foolishly spray any brand of "contact cleaner" in to any pot or linear fader there will be no risk of stiff or frozen movement of any control afterwards !
Use the right product like Caig fader lube when spraying pots, not some contact cleaner that will surely wash out any lubricant, and could very well weaken or destroy the track inside !
I never did for over 45 yrs. servicing all manner of analog electronics, I guess because common sense deemed not a good idea to do so..
I have never forgotten the first edition of the tube amp book, where some imbecile recommended Gunk Choke and Carburettor Cleaner for cleaning controls. That little piece of stupidity paid a fair chunk of my mortgage![]()
And also in the same early Aspen Pittman Tube Amp book, IIRC. some notable West coast instrument tube amp repair guru guy indicated that he flushes the amp`s controls with WD 40, as well, during his servicing !
Never tried, or thought about even trying that stunt, with RS`s TV tuner & control spray readily available during the eighties until they removed it from the market because of the CFC propellant in the early nineties.
I used cases of it with zero problems during that period, even on several high dollar 7 ft. wide 48 channel live sound mixing boards for a local live sound company and all vintage guitar/bass amplifiers, whether tube or SS brought to me.
Do you also remember the part where they said to bias up an SVT to 0.72V instead of 0.072V? Worked out to about 240mA idle current per 6550. Worst part, that fifteen pound HV transformer could easily supply the current. Good thing we're fan-cooled
An expensive experience for several wannabe techs...