Hello everybody:

thank you for all your suggestions, I have already repaired/adjusted the
power supply, some switches and the optical encoder.

It seem the 100 KHz resolution filter does not work properly (83 KHz of
error in bandwidth according to the internal calibration routine) and the
1st LO sometimes fails to lock at low frequencies...50KHz-200KHz.

Does anybody have any suggestions? I have all the manuals and trying to
solve it.
Any place where I could get working modules or board extenders???

Thank you