> i tried this but it doesnt help here, when the 126 is not working there
> seems to be no way to change this for the day. on next power up
> or some days
> later its sometimes back to normal for a while.

Are you able to do some simple measurement I'd like to know if the
quadrature VCO is the problem, i.e. you would have to check if the
sine/cosine waveforms are present while the A-126 does not work. They are
available at pin headers on the pc board of the module (no soldering
required, it would be sufficient to touch the corresponding pin of the pin
header with the tip of a patch cable with the other side connected to an
audio mixer).

Best wishes
Dieter Doepfer