Editing Amstrad CPC 664 Maintenance Guide (section)

=== 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.