Editing Amstrad CPC 664 Maintenance Guide (section)

== Floppy Drive Maintenance ==

The Hitachi 3-inch drive in the CPC 664 has three known wear items:

=== Drive belt ===

The drive belt is a thin (0.5 mm) flat rubber band that drives the disc spindle from a small pulley on the spindle motor. After 30+ years, the original belt is almost universally either liquefied (a sticky black residue on both pulleys) or stretched past usable tension. This is by far the most common 664 fault.

Symptom: '''disc not detected'''. The drive motor runs but the disc does not spin, or spins for a fraction of a second and stops. The system reports "Read fail" or hangs at CAT.

Procedure:
# Remove the floppy drive from the case.
# Remove the drive's metal top cover (2&ndash;4 screws).
# Locate the rubber belt running between the spindle motor pulley (at the front-left of the drive) and the disc spindle pulley (at the centre).
# If the original belt has liquefied, clean both pulleys thoroughly with IPA on a swab. The liquefied residue is a sticky black gum that can stop the new belt from gripping.
# Slip the new belt onto both pulleys. Modern replacement belts for the CPC 664 / 6128 / +3 are available from dedicated Amstrad shops &mdash; '''54 mm &times; 1 mm flat rubber drive belt''' is the most common spec, but verify by direct measurement of the pulleys.
# Verify the belt sits centred on both pulleys, and rotate by hand to confirm there is no slip.

=== Pinch roller and head pressure ===

Less common than the belt but eventually relevant. The pinch roller is the small rubber wheel that presses the disc against the spindle when a disc is inserted. After many disc insertions, the rubber hardens and develops flat spots, causing the disc to slip at high speed.

* Replacement pinch rollers for the Hitachi mechanism are available as modern silicone-rubber parts.
* Head load pressure: the head is sprung-loaded; do not adjust the spring tension by bending the bracket &mdash; the alignment is set at the factory and is not field-adjustable.

=== Worm drive / stepper lubrication ===

The stepper motor moves the head radially across the disc via a fine-pitch worm-drive lead screw. The worm drive needs '''light machine oil''' (e.g. clock oil or sewing-machine oil) every 5&ndash;10 years. Symptom of dried lubrication: stepper makes a chattering sound and the head fails to seek properly, often reporting "Track 0 error" or "Disk error" when accessing a known-good disc.

Procedure:
# Remove the drive's top cover.
# Locate the worm drive (a 2&ndash;3 mm-diameter threaded brass rod connecting the stepper motor to the head carriage).
# Apply a single drop of clock oil to the lead screw at the head carriage end and the stepper end.
# Move the head fully in and out by hand a few times to distribute the oil.
# Avoid getting oil on the head itself or on any belt or pulley.