Excellent advice given above and as an owner of a 475A and two similar 465B's I can give a few hints that have worked for me.
For the pots. Even though they are supposedly sealed depending on type used the gap between the plastic and metal is enough to get cleaner in there without prying and risking damage. For this application I use Dexoit D100 and just spray it on top of the control and let it soak in. Twist the pot several times. Usually get decent if not perfect results.
For the switches basically same method. D100 on the exterior of the control.
The attenuator switch decks are a whole different animal. Yes, absolutely correct method is disassembly and cleaning with coarse paper and IPA. But disassembly not easy. I have gotten good results by direct spray of 100% IPA on the decks with them in place. But remove the attenuator blocks first. Then dry with a heat gun. Sometimes one or two positions still will have poor contact. Typically the 0.2V and 20mV range. In this case I will use a SMALL amount of dexoit D5 soaked in a cotton swab directly on the finger contact. Be careful and make sure no fibers left behind. If that doesn't work then unfortunately it will have to be disassembled and cleaned. And I have run into one instance where the deck was worn beyond repair and had to salvage one from a parts unit.