Longarm Quilting Machine Jammed?

My longarm quilting machine jammed, and I disgorged a lot of thread, but the shaft doesn't turn and the motor grinds when I turn it on. I know it isn't a thread birdnest anymore, causing my machine to freeze. Could it be that the motor belt was torqued? The handwheel is just as tight as the shaft. I'm using a Nolting Hobby Quilter, and I love it! Just help me out of this (literal) jam, all you quilting gurus, please.