Modded Marshall Amp Build - Signal when Gain pot is at 0

[Dror520]

Hey guys,

I built a modded Marshall style amp that I kept modding through the years. It has a Plexi and Hi Gain mode switch.
I recently noticed that there's a very low signal still being heard when the gain is at 0.
It's much louder on the Hi Gain mode and It goes away when I turn the master volume to 0.
I've been trying to troubleshoot this, but can't seem to figure it out. Is this normal behavior or is something wrong?

Thanks!

 

[WarHed]

Some pots just dont get all the way to zero, or there's a ground offset on the pot. Nothing out of the ordinary.

 

[glpg80]

Bad ground for the gain pot or the pot wiper needs contact cleaner, or both.