Editing Sinclair QL Microdrive Troubleshooting Guide (section)

=== Head springs ===

Weak or distorted head springs cause poor cartridge compatibility — the drive reads its own tapes but not others'. Viewed from the front of the drive, the top of the springs should appear roughly level with the bottom of the lower head guides.<ref name="sm" />

The springs can be tested functionally with the signal test program: write to a tape and note the peak-to-peak read level, then twist the cartridge clockwise and release, and anti-clockwise and release. The level should return to roughly the same value. '''If the level drops significantly after settling for about 7 seconds in either direction, there is a problem.'''<ref name="sm" />