Gas powered clothes dryer not spinning, but blowing hot air. Can it be fixed?

My boyfriend has had the absolute day from hell, and just as I was getting him cheered up again, we discovered that the dryer wasn’t spinning. He took it halfway apart and can’t see anything wrong with it.

He’s upstairs showering now, and I’d like to maybe have good news for him when he comes back. So, can it be fixed? Or is he going dryer shopping tomorrow?