I have a DCC 600 that plays fine but keeps switching to side B often. When I look at the tape I never see any problems with it. It does this with new tapes too.
You might also clean the head intensively. Switching to side B is usually a dirty tape or head.
It could also be the gear, pinch roller or belt. But I believe they are all replaced.
I will do the head and pinch roller cleaning and see if that helps.
It’s been a while since I’ve seen schematics of 2nd gen machines, but doesn’t the 600 have an optical end-of-tape detector? If so, that might be the problem.
I did the deep cleaning but it is still doing the same. I noticed that it also fails to rewind the tape to the beginning on many tapes, it goes into STOP. I have to press rewind to continue and then it does get to the beginning. The same tapes work perfectly on the DCC175.
Does the TOC show correctly during rewind of the tapes / time and tracks?
Yes. Time and tracks are being displayed. It will sometimes just stop during rewind and not show the word STOP on the display like you normally would see when it reaches the beginning of the tape. I will continue testing with different tapes and will post results.