Tektronix 11403 - Error G3731 on Digitalizer Board

[scroky]

Hi,
after a few months of non-use the my wonderful main frame Tek 11403 complains about replacing the lithium battery of the CPU board when it is turned back on. I will replace the two lithium batteries on the mainfraime, but continuing the diagnosis, now i will complain about the error G3731 in the DIGITALIZER / POINT ACQUISITION / AD Voltage section with a variable measurement -0.864 ...- 0.851V while the correct interval is -0.750 .. .-0.850V.
Furthermore the enanched accuracy is no longer available: ENANCHED ACCURACY FAILED: MAINFRAME: MAIN TIME INTERPOLATOR. PLUGIN NA. TRIGGER NA.
It seems a problem that cannot be easily solved since the manual does not provide indications on errors and on chip level repair, but only on board level reapir.
Does anyone have any experience with this?
Thanks
Alessandro