I am new to this forum and getting back into guitars after a 20 year layoff

My Fender Dual Reverb was in the attic and the knobs had stuck. I assume the grease in the potentiometers solidified in the heat. They are movable but do not move without making noise.

I didnt find threads on cleaning them yet

Any advice? I have chemtronics solvent and am mechanically and electrically inclined

I also have to look at the reverb as well since it is not working. I see it sealed in the plastic bag in the base

thanks in advance !
Contact cleaner for all the pots and jacks. Also all the tube sockets need cleaning. Test your spring reverb with an ohm meter to see if it has continuity. Usually the problem is contacts or tubes and not the spring unit in the bag. Be mindful of your circuits if you open the chassis. Tube amp capacitors can kill you quick even with the amp unplugged.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY
I had a Twin in a closet for 20 years too. When I finally pulled it out it was covered in mold, but it came off easily to original finish. It also needed another mod. The amp was bought in the US and brought back to Australia (and straight into the cupboard). It wasn't equipped to handle 240 volts, so now sitting in the base of the cab is a big step down transformer, which also contributes a big dollop of weight.
I plugged it in and it didn't miss a beat, until the first gig. I'm in the middle of a big solo and the amp starts smoking big time and we closed down mid song. In for a full service and it turned out to be mold in the tube caps.
The tech called me in a complete tizz asking me where I got this amp. He said it was one of the first batch of 200 Silverface amps that still used the Blackface circuitry. He was gobsmacked that the amp chassis was still pink and wanted to buy it there & then.
It is back in the closet now.
Thanks for your help .

I re-installed the tubes but I don't see how to access the chassis to clean the pots.

I do see 4 nuts, on longer bolts protruding out the "bottom" of the chassis but that can't loosen the chassis from the cabinet. Maybe that just allows the cover to come off and the chassis doesn't slide out of the cab?