That is good to know, I learned something new today (pulley has adjustment). The first time I engage the PTO on my new X540 the belt came off the 47" blower. Not a good first impression. I adjusted the lift height a little and found it would still do it if I engage the PTO when the blower was raised. Since then, I make sure the blower is down when engaging and have not had a single problem since. I'll keep that adjustment in mind if things change. Im surprised JD does not send out a letters to pertaining customers to advise them of the bulletin, issue, and remedy. I know it is probably a way to save for them but it would be nice to know without having to talk with a dealer to find out.Yes, pulley alignment (akin to fleet angle) is critical on this arrangement. In fact, when my blower was delivered, I had a heckuva time keeping the belt on. Fortunately, there was a bit of adjustment available in the elevation of the driven pulley (two setscrews on the underside of the pulley) to allow raising the driven pulley and remedy that problem. Throwing the belt must be a rather common complaint because JD issued a bulletin regarding this issue. Raising the blower to a higher elevation, and thus raising the driven pulley, would only contribute to this potential problem.