cassette/tape deck sensors/readers; what can I do with them?

So, I was at my girlfriend's apartment when I came across a busted tape/cd deck underneath the porch and immediately though "FREE parts!" like any self respecting modder would.

The circuit board, in pieces, has been subject to the elements for quite some time, the device made in 2002, I've no idea though how long it has actually been under there.  ("new" place)

So two questions.
1) Are any of the components (capacitors, diodes, resistors) safe to use, assuming they were not short circuited by rain/humidity and rust hasn't set in?  (On some parts it has, the motor turning the tape deck being the main and most unfortunate one.)

2) WHAT could I possibly use the sensors/readers that read the tape of the tape deck besides reading the magnetic tape inside cassettes?!  I came to the conclusion that reconstructing a tapedeck with these sensors would be impractical, if not stupid.  Can they sense any magnetic field?  Would it be hard to write an arduino library?

I tried looking up a datasheet and get nothing that resembles these, much less something that might belong inside a tape deck.

15RSA0
J2
K1520

Is how it appears on the side of the part, the 0s might be Os.  But the rest is pretty clear (I love a nice font).