On MAC 2000 Washes produced to date, the zoom belt may ride up against the lip of the pulley closest to motor in "hyper" mode, when the zoom lens is all the way back. To improve the alignment and reduce wear and tear on the belt, we are raising the pulley slightly by inserting an additional brass washer.
Serial number information for this change is not yet available.
If you find excessive wear to the top of a zoom belt, you can improve alignment by adding a "Spacer, D=5, d=3, 2x1, brass", P/N 17800340 under the pulley closest to the zoom motor, the one that does not pivot. You will also want to replace the 12 mm metric screw with a 16 mm screw such as P/N 08050506, "M3x16 screw, Phillips, cs, black"