Ronald Finger on Youtube has a GREAT Fiero restoration series. Its worth watching the whole thing but he has a video just for restoring his radio. Here's the link:
https://www.youtube.com/watch?v=CXJLkxzgnwAI also need to rebuild a dead radio. I suspect most issues to be simple, just a matter of finding them:
-deteriorated rubber cassette belt - replace, apparently there is a pack of multiple lengths available on Amazon
-bad/broken solder joints - reflow with flux and an iron
-replace bad capacitors (electrolytic caps tend to start to go out of tolerance in 10-20 years and will sometimes bulge, replace all the bulged ones and go from there)
[This message has been edited by Alibi (edited 04-07-2021).]