I have an unexplained issue. Left channel does not work in stereo mode when tape selector is set to source, which is straight up. Both channels do work in mono. Both channels work fine in stereo if I have the tape selector set to source mon. Whats up with that. Everything use to work fine on tape source, but recently left channel no workie in stereo. I have done a complete de-oxit job but nothing has changed. Like I said, works fine set to source mon.