Working on a 100G.  Both of the mute switches are working well. The problem is that when the record starts to play, if it take a little while to get into the song, I hear a hum in the speaker, when the song starts, the hum gets mostly hidden by the music. The same thing happens at the end of the song before it cancels and closes the mute switch.  Oh, in the beginning of the record the hums comes on slowly do to the squelch circuit.

Pulling the RCA plug out of the amp yields no hum, the hum is coming from either the mech or the mech wire.  I've tried shorting the two different (one at a time) mute switches and the hum goes away.   Also shorted the tone are wires and again, it has no hum. Also checked continuity throughout  the mute circuits and all seems fine.

Thanks,

Tony