Over Compression

Confirm the last time the belt was deep cleaned.
The belt should be deep cleaned weekly. If it has been more than a week, follow the instructions in this link to deep clean the unit: https://www.youtube.com/watch?v=3dp69-zcKOg&feature=youtu.be
Check the compression lever on the unit.
Compression should be set on 5.
If the above steps don’t resolve the issue, call for service.