Autodesk Inc. I post here the procedure.
Any feedback is welcome.
The voltage at the outputs can be corrected in two ways. If you don't have the service manual, the correct points are positive pins of electrolytic capacitors C825 and C826. These capacitors can be found next to the larger shielded box on the RF board, on the side close to the loudspeaker. After installing these resistors the suppression of the unwanted sideband improved in my receiver from 14 dB to 20-26 dB, and I think the distortion is reduced too. These components are shown on the factory test circuits of the chip and also in the article on synchronous detection by Mike Gruber in QEX, Sept. '92, pp.