Sounds like a gear may have slipped. The gears are easily accessible if you take the speedo section out of the instrument cluster. That way you can visually inspect everything and order new gears if necessary.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth