Originally Posted by platzangst
Cleaning tape heads can be done with a cotton swab and a bit of isopropyl alcohol. A lot of points in a player can be cleaned with alcohol - capistan, guides, but not the rubber pinch roller. Use only soapy water on that. Depending on the age and condition of your player, you might invest in a demagnetizer, too.
Pinch rollers and other soft parts of the tape path can be safely cleaned with denatured (not isopropyl) alcohol. It can be hard to find, but it works.
Also, agree with using external tools other than Reason to clean up the sound. Audacity is free, and comes with filtering and background noise cleanup functions. You can sample a variable-duration portion of the tape that contains only background noise, and it will attempt to remove it from the entire recording. Variable success rate, but better than nothing.
For me, the hardest thing to deal with on old cassette recordings is speed variation ue to poor storage/handling regimes. (I.e., played the tapes in my car and left them in the glovebox for months at a time, etc.) These wow and flutter components are extremely difficult to deal with in getting decent files from tapes.