[mott]

The suggestion about the motor shaft being too long is the most likely scenario. We typically have to trim down the motor shafts after pressing on our pinions.

One way to check for this is to gradually loosen the 4 bolts that span between the mounting block and the face plate of the P60 and try to rotate your P60 output shaft as you go. If loosening these bolts eventually allows the assembly to turn, then the shaft length is sure to be your problem.

One valuable hint on this shaft length fix is to press your pinion onto the shaft BEFORE trying to trim the shaft. It's much more difficult to press the pinion on after grinding the motor shaft. Also, be sure to tape up all the openings in the motor before grinding on the shaft so you don't get metal filings in your motor. Finally, don't let too much heat build up while grinding down your motor shaft or you could damage the motor. Hit it hard and fast or take your time and let it cool down between passes.