seriously, they still make those? i remember when i used to make mix tapes and bump MC Hammer.
anyways,
have you tried using that cassette head cleaner stuff? it also may have to be demagnetized.
either way, more likely, you wont really need to open that bad boy up to take care of it.
better yet, oren, dont you have an extra deck you can sell him?
good luck with that, i guess it couldnt hurt to take it apart to take a look around. dunno about the Gen4s, but my guess is you'd need to take the trim off first to get to the screws for the deck.