This may simply be bad contacts somewhere, I had
the same issue with a TRV330, and it was solved by opening it and generously cleaning the ribbon cable contacts and electronics with with electronic cleaner (don't get that stuff on the tape path or on the oiled mechanism though.) Unfortunately it later developed other issues. Be very careful when opening if you decide to try, as the ribbon cables can be quite fragile.
Also see this video
of a (former) repairman fixing a DCR-TRV130 with a similar issue.