Cassette deck cleaning

Rubbing alcohol on a Q-tip will work.
Note: Clean the rubber wheel by holding it in place with one Q-tip while scrubbing it with another.
VERY IMPORTANT! Make sure the entire rubber wheel is dry be fore playing a tape. A wet wheel may cause the tape to stick and spool out on to the wheel!
Finally try to obtain a demagnetizer and degause the heads.
If too much magnetic charge, the heads will actually erase delicate high-frequency signal permanently from the tape!

Well, If you don't demag first, be prepared to have anything you play permanently changed. The exception to this is "Metal" tapes. What made metal cassettes popular is they require a much stronger electrical signal to record and, consequently, they require a stronger signal to erase.
This makes them resistant to passive erasure.
Good luck!