Apple 7200/120, WS 7250/120, 7200/90 manual

	Troubleshooting		Symptom Charts/Floppy Drive - 16
MS-DOS drive does		To read and write files with either MS-DOS or 1.4 MB drive,
not recognize a disk		format all disks with MS-DOS drive first.
formatted on a 1.4 MB
drive
Internal floppy drive		1	Replace disk with known-good floppy disk.
runs continuously		2	Replace floppy drive cable.
		3	Replace floppy drive.
		4	Replace logic board. Retain customer's DIMMs.