Hello Nick
Welcome to Beoworld and very pleased to see that you have signed up as a gold member. I am surprised that no one has replied to your enquiry but VCRs don't seem to be a popular topic these days. I have two, the V8000 and the VX7000 and they are both slowly deteriorating over time. When they eventually give up the ghost, I don't think that I will be in a rush to repair them. The weakness is of course in the recordings - I still have 30 tapes but their quality is now very questionable.
I am afraid that I cannot offer a solution to your problem but it does sound very similar to one that I recently had with the V8000. It too was playing back OK until I inadvertantly put in a very bad tape. The tape transport jammed, the speed was wrong, the video disappeared and the audio was bad. I probably spent too much time trying to get it to work but I didn't appreciate that it was a tape problem at that time. When I finally ejected the tape and put in another one, that didn't work either. Neither did the next one too and I thought that the machine was now broken. After a few days, I had another go. I put in one of my better known tapes and fast wound the tape to the end and back. Pressed play and everything worked fine. The tracking seemed to be a bit off but that was corrected and the unit is working once again.
So maybe, these units are just becoming more sensitive to deteriorating tape quality. I can't think of a solution to that one and I probably will never play those tapes again. Now that we have the PVRs, it is perhaps time to put these machines into storage until they aquire antique status.
Regards
Geoff