There have been many complaints about the transport system in the XM2 camcorders. I’ve had my camcorder in for service at Cannon 4 times now within the last 7 years. With problems ranging from playback to firewire (ieee 1394)connection problems to recording issues. All repairs lasted no longer than 6 months.
Recently (after reading this and other post), I did try using a contact cleaner on a q-tip, applied it to the white gear with the black gear release on top and now the camcorder is working just fine.