Well... at least I could recover the PC floppy unit. But it took some time
and one diskette with clean liquid (not a cleaning diskette... I needed to
improvise).
I've always found it best to remove the floppy drive and clean the
head(s) with a cotton bud soaked in propan-2-ol. At the same time I clean
the optical sensors (index, track 0, and write-protect, as applicable),
since dirt there can cause all sorts of problems.
-tony