Belt is coming off upon engagement.
As you say, when under tension it runs good.
Dealer showed me how to keep auger running continuously, even in reverse, which helped some.
But there are times I need to disengage, for example cleaning the chute of clogged up snow, and when I re-engage the belt pops off and I am stuck shoveling.
Extremely frustrating!!!
Seems like it was not properly designed?