unreliable 1665

[rootbeer7]

Please help: I have a 1980's Gt White Sea Dweller I purchased just over a year ago. It is proving problematic in that it appears to keep stopping despite a full wind and being worn continuously during the day. It seemed to stop in the evening and when I sent it back to my dealer who sent it to his watch specialist he felt it may have something to do with the date change mechanism. It was cleaned and oiled etc and on a watch-winder behaved perfectly for 2 weeks
I have it back now and it seems to be doing the same thing albeit after 36-48 hours.
Does anyone have any ideas?
It appears to work on a watch-winder, but irregularly on the wrist.
Thanks in advance