Editing Sinclair QL Microdrive Troubleshooting Guide (section)

== Community-reported faults ==

Alongside the Service Manual's fault tables, these are the problems QL owners actually report on surviving drives today.

* '''The cartridges are usually worse than the drives.''' Forty-year-old tape loops shed oxide, the felt pressure pad hardens or falls off, and the lubricant dries out. A drive that fails every cartridge may be faulty; a cartridge that fails in two known-good drives is simply finished. Sort your cartridges before condemning a drive.
* '''The drive roller is the usual mechanical culprit.''' The rubber goes hard, glazed or sticky, which produces exactly the speed instability and read errors that the signal test shows as a waveform unstable in the X axis.
* '''A dead ZX8302 stops both drives.''' If neither MDV1 nor MDV2 will even spin, the Service Manual's remedy is to renew IC23 rather than to look at the mechanisms.<ref name="sm" />
* '''One bad drive can disable the other.''' Some early Microdrive ULAs fail to tri-state their data lines when inactive, holding them at about 4.5 V and preventing the other drive from working &mdash; while themselves appearing to work normally.<ref name="sm" />
* '''Formatting to a low sector count''' is a worn-tape symptom rather than a drive fault. A healthy cartridge formats to a little over 200 sectors.<ref name="froschle" />