The problem was a very simple issue in the end. A bolt... One... fell out. However it's the bolt that holds the main pulley on. As the bolt backed itself out the pulley worked it's way down and this model has a plastic cage over it. The pulley began eating it's way through the cage--- that was the ratchet sound and the burning smell. I put the bolt back in with a new lock washer and it has worked fine ever since. Total cost was 3 cents for the washer.