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.