See attached. So I'm trying to remove the rear pulley, which sits under the gearbox / seat area. Unlike the front pulley, which had a standard shaft through it, this one has a thread bolt. I've removed the nut and locking washer, but no matter of force will get this one to come off. Why is the shaft a threaded bolt? How do I remove the pulley - the belt stays are welded to the frame, so you have to lower the pulleys to change the belts.