It also may be the case of worn floppy-insert detection microswitch - the one that consists of two small "fingers" just in front of the loading slot. I had this issue in my A4000 floppy drive. What it was, it actually thought the floppy was in, when there was no disk in drive, and there were these noises as the drive was trying to read non-existing disk.
I'd suggest replacing the whole floppy drive, or try reviving the microswitch somehow.
