The V1 is responsible for the input stage and tone control return. If it is going bad, you can have noise or scratchiness on the pots you mentioned. If you replace the V1 and still have issues, the other maintenance below may help.
When the wiper hits a spot in the sweep that does not conduct it will hum, either from being dirty or the resistor element has worn down. I would clean the pots and lubricate them with Caig DeOxit and then Fader Lube. You can also get noise from a dirty preamp tube socket, which may make it seem like a faulty tube. The V1, 3 and 4 are a good start to clean and retention the tube sockets. When there is dirt or oxidation, the tubes will crackle when they are wiggled. The noise is increased in lead mode if the V3 and 4 are dirty or loose. I use a dental pick and a jewelers flat head to tension the sockets, then I spray them. I do the same for the power amp sockets. While your chassis is out, it may be a good time to clean the grounds. The star ground just below the back of the power board can be soaked and the preamp ground, which is a braided wire can be shot with contact cleaner. I use a paper towel behind the wire to prevent the solvent from getting all over. Shoot the effects loop jacks from the back side with a 1/4 in cable inserted 1/2 way to open the contacts on the return. You can use a paper towel to catch the solvent exiting out the font side of the jacks. You can also clean the input, reverb/eq, and speaker jacks. For shiny new 12A jacks, you can cut a 1/4 inch strip of Scoth Brite 0000 and insert it into the jacks and pull it back and forth, buffing the contacts. I never clean the EQ faders and try not to clean the slave pot. Once you remove the lubricant from them, they never feel right again. When everything is clean, you tend to have less frequent issues if any at all and it's really easy DIY maintenance.
