Originally Posted by RANDY P

Unfortunately, there is no real way to accurately diagnose whether or not the deck or amp is bad without actually swapping the pieces out.

I would check all your fuses, and if they pass then the next thing I would suspect in your case is the amplifier, it's the one doing most of the work.

I would source a good used amp (should be cheap) and a new head unit with CD- upgrade upgrade upgrade..

Who uses cassette tapes these days anyhow?