Here is an old thread I found and it works for some cassettes that have erratic play problems. Just be VERY CAREFUL! In the screw wells on the back there are three holes on the sides at the 12,4, and 8 O'Clock positions at the bottom of the wells. If you set a screw and forget, set anthoer one on top and attempt to screw it in it will slip off the side and into this hole. If this happens, have plenty of scotch and be prepared to drill it out. Dumbest thing I ever saw. No fun.

Heres the thread:
Panasonic RX-DT680 Cassette Fix

Hey oldskool69, I did the exact thing with those leaf covers and used contact cleaner nothing. They look pretty clean but I noticed adding pressure to the leaf switches I noticed on the display it shows (tape 1) and the direction of the tape to play. When pressing the play button you only hear a ticking sound but the tape head does not activate neither does the capstans rotate. This only works on (tape 1) I've tried tape 2 nothing at all. The belts are fine I've noticed on the bottom of the tape deck there's a white gear peeking out throuh a small hole thats the one that move's but on short intervals. I've also noticed while pressing the leaf switches and pressing FF or REW you can a humming motor like sound but no movement at all!

I just have to say I used the method the cassette issue thread which olskool69 advised and it work my recent RX-DT680, my second one also but my original it's more mechanical so it definitely will need to go to Panasonic factory service center which is very near to me. Thanks oldskool for pointing the way to resolve my issues.

Glad to hear it. These things arent getting cheaper to fix so when we can do it ourselves it's great to have this site to turn to. As a side note this will also work with othe logic controlled units with similar setups.