Doepfer

my a126 freq shifter suddenly stopped doing his job.
the audio output still works at normal level but the 3 shifted outs (up, 
down and mixed) are very silent
and there is no effect to be heard anymore.
the overload starts clipping at 3 already - input is an osc sawtooth 
directly.
when the mix poti is in middle setting - the signal is almost mute, 
extreme left and extreme right does give
a very silent signal.

anybody has an idea what could be the problem ?