#1
I recently retubed and biased my Jet City with a set of JJ power tubes. The amp sounds great right now, except for the fact that the Bass and Mid knobs have no function. The Treble knob however, directly affects my volume. Everything else works as it should.

I have tried swapping in a known working preamp tube ( I had 3 spares ) in each slot, but that seems to have had no effect. I also had to clean the overdrive pot with some contact cleaner to make that channel work again.

What is my problem here? Are the rest of my pots dirty? Is it a preamp tube? Or is it the circuitry itself? I have a multimeter and some electronics experience if someone can help guide me through troubleshooting.
Rig:
Jackson SLSMG/Ibanez S470QS/Charvel DS-1 -> JCA100H/BV50H -> Carvin V212

Quote by JamSessionFreak
Some of my farts last longer than Axe does.
#2
Clean all the pots and see if you get anything better
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#3
Just attempted that. No difference. I just now noticed that the mid control pot is much easier to spin than every other pot as well.
Rig:
Jackson SLSMG/Ibanez S470QS/Charvel DS-1 -> JCA100H/BV50H -> Carvin V212

Quote by JamSessionFreak
Some of my farts last longer than Axe does.
#4
I'm just posting here again in case anybody else ever has this same problem, and needs this as a reference.

I took the amp to a local guy to get it fixed, and it turns out that some of the jacks were poorly tightened, giving them a bad ground connection. V4 also had a bad connection on one of it's pins.
Rig:
Jackson SLSMG/Ibanez S470QS/Charvel DS-1 -> JCA100H/BV50H -> Carvin V212

Quote by JamSessionFreak
Some of my farts last longer than Axe does.