🚀 go-pugleaf

My wife has an long-standing collection of cassette tapes and over
time many of them have begun to squeak.  Typically the tape starts
in good shape and at some point faint metallic mosquito noises appear
and then go away.  Then they get more persistent and louder.  I can
tell you that you don't need much of this to ruin a good musical
piece.

Why do the tapes do this?  Have they been played too often?  Is the
tape deck ruining them?  Is there any way to salvage the tapes or
should they go to the trash?  Please send a copy of your reply by mail.
Thanks.