I bought one new in '78-'79 from Sound World (now Best Buy), $169 I think.After about 5-6 years of normal use the playback/record head developed a groove, and started ruining the edge of the tape creating dropouts. I still have it, + the box+ manual. I'm sure it needs belts as well. The performance vs repair cost didn't seem worth it, why I've held on to it-who knows?
It was a okay machine, not impressed by the quickly worn head ( I keep my heads clean and demaged on a regular basis).
The Harmon Kardon CD91 I bought to replace it totally blew the Pioneer away in terms of frequency response and recording. Of course it was a 6 year newer product-Cassette decks really improved in the 80's compared to their 70's counterparts.
Minimum I would check the head(s) for grooving. Unless you have the parts handy, seems like