CURE:
1. Remove the drive case and examine the drive mechanism.
Locate the label on the drive's stepper motor. If the label is
circular and on the flat end of the stepper motor facing the rear
of the drive, then the stepper motor is compatible with any rev of
Macintosh boot ROM and if the drive fails MacTest, it should be
replaced .
2. If the label is square and on the curved part of the stepper
motor, then you need to check the ROM in the Macintosh to make
sure it they are revision B or later. A square labelled stepper motor
is not compatible with revision A ROM in the Macintosh. If the
customer's Macintosh has revision A ROM installed, install revision B
ROM to make it compatible with the disk drive.
If this cure does not solve the problem, go to the Technical
Procedures to obtain a general troubleshooting procedure for this
product.