I have the same unit as you do and had the exact same issue. The issue is the motor gear engaging with the gear that drives the unit out. They chatter and slip. There is a fix for this that works very well. It is detailed at the carriage cameo site by a user named Falcon Hunter. All the parts needed can be found locally and costs less than 40 bucks. I did the fix on my unit 2 years ago and it has worked very well every since. If you can't find it contact me and I'll be glad to help you out. my email is jlott@csa.canon.com I struggled with this problem until I found this fix!