I have a 1991 740 turbo wagon that has the original working radio, and tape player, which isn't quite as functional. radio has no issues, besides radio sucking, but when I first got the car I tried 2 different tapes that I knew worked and neither played. today I got a cassette adapter and while it works, I have to turn the volume all the way up on the radio (it's up all the way on the device already too) and even then it's pretty quiet.

any thoughts on what the issue could be here? or ways I could potentially fix it myself?

 

i haven't had a cassette deck plugged into anything for 10 or 15 years, but I'm vaguely remembering those cassette adapters only worked in some stereos