Need to figure out why channel 2, the instrument and mic channel is not working. Channel 1 and mic only channel are working fine. Opened it up and took out the chassis and there is nothing obvious. The basic schematic shows the Channel 1 and 2 share the instrument input on the ring cable input. Not much info out there which is good news considering this amp has been in production for a while so it doesn't seem there was on going  issues. Any ideas? Thanks