The belt derails often. If you look carefully at the pulley, it will appear to be out of line. Many times, the bearing wears out. When this happens it gets noisy, often a squealing or screeching noise.
Now that Balrog has given an appropriate answer, I can post mine.
Look to see if the fender crack is showing.
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them