YES solved… What gut feeling can do . I always felt belt causes the problem.
@DrDCC, the grease part also crossed my mind so i did clean both the wheels and all belts, even washed my hand to remove skin grease" in order to operate as clean as possible, but with the first 0,8mm belt this wasn’t the solution.
This afternoon I received my third belt. I tried 0,8mm which didn’t work (slipped due to resistance of the pinchrollers mechanism). Then tried 0,6mm snare which seems to perform fine during manual testing but failed during playback (intermittent playback, lots of error during head service tests). As said, today received the third belt (again a 0,8mm ) which finally solved the issue and performs prefectly .
The DCC 175 went easy while this DCC 170 was a real “pain in the ass”. Both 0,8mm belts I tried in my DCC 170 came from same supplier (same like the 0,8mm belt used in my DCC 175), so could be bad luck with the first one i used in the DCC 170.
I hope this information help others (e.g. pvdm) to solve your issues. Luckily it wasn’t a speed issue problem as this seems more complicated to calibrate the motor speed based on a 440Hz or 3000Hz recorded analog cassette. But due to this I learned a lot about that as well, but even more on how to repair the portable DCC’s. With that knowledge in mind and combined with the knowledge to solve many DCC 600 and DCC 730 problems, I might open my own Europe DCC Museum and become the “DCC Professor” … . If I do so, Dr DCC will be the first and main guest to open it .