Seriously, even a very high quality cassette deck is scarcely worth
repairing these days.
I have found a better bet is to advertise things "all faults" declared on
eBay, and hope that some enthusiast offers you a reasonable price and has
the nouse/spare parts to repair it themselves.
I got rid of a non-working ARCAM DAB tuner this way for over a £100.
Good luck.