When the cassette player failed in our '87, we opened it up and found that there was a spring that had gotten weak. It was designed to stretch when the tape pulled too hard, or got to the end of the tape. We just reattached the spring hook in another hole further away, such that it pulled harder, and the cassette worked for several more years.

As noted, give it a good cleaning while you are in there. I wouldn't take it to a shop, as that unit is not worth spending any $$ on.

When we replaced the radios on our bricks, we had to cut the old radios out of the faceplates with a dremmel tool in order to have the dash piece we needed to cover the hole.