hifi engine

Technics SU 7600

I have a Technics SU 7600 integrated amp that was working fine then the left channel started to output nothing but static. Re-soldered everything pertaining to that channel and de-oxed the pots and switches. Intensity changes when I move the brown and gray wire from the speaker selector switch to the mainboard. Which I have already re-soldered. Could this be a bad ground?