@philtomo
you could also try (if you have a valuable collection, and want floppy-copies) buying a catweasel controller for your pc/amiga.
the catweasel controller is like a super-floppydrive wich has very good reading algorithms that can read disks that don't copy well in other drives (this isn't guaranteed ofcourse).
what you end up with is the contents or an image of your contents on your pc hdd or on your amiga (then to be transfered to another floppy, in your case).
the catweasel is an expensive solution though, but it's main purpose is copying any disk from the amiga to the pc or vice versa.
for the controller you would need a standard pc-floppydrive.
taken from the seller's site:
"Sophisticated error correction algorithms enable you to read otherwise unreadable disks. In other words, you have an excellent chance to read your formally unreadable floppy disks."
it can also provide for using the controller with your amiga, with the same abilities, it's supposed to be up to 2.6x faster than standard amigafloppydrives and makes you able to use hd floppies with the amiga.