- Intermittent or open connection of the speed sensor (reed switch) wiring.
- Reed switch is defective or has an intermittent connection.
- Drive motor brushes are bad.
- Lower PCA is bad.
- Inspect the speed sensor (reed switch) wiring for damage or poor connection to the lower PCA. Replace damaged wiring or reset connection as necessary.
- Using an ohmmeter, test the reed switch while rotating the drive pulley. The reed switch will close when the magnet passes in front of it.
- Inspect the drive motor brushes and replace them if necessary.
- Test unit with a known good lower PCA. Replace lower PCA if necessary.