I would first clean the heads with a disc cleaner (made for that purpose) available from many places including Amigakit. If it is out of alignment, aminet has a program with instructions for just that purpose that works quite well. However the heads do go bad and quit reading. You may be able to just pull you external floppy drive from its case and put it in your A2000 with no modification -- brand dependent. Otherwise Amigakit sells $30 USD floppy drives.
Please note: "DH0" = Drive Hard (0); "DF0" = Drive Floppy (0)
