Originally Posted by Al.Fisherman
First of when you get the gear puller, make sure the threads are good. You may need to take a small 3 corner file and work on the teeth. Make sure that the tool is bottomed out when threading it on to the gear BEFORE you attempt to remove it. When installing the woodruff key ensure that it fits correctly (in the key way and gear). Then take a drop of super glue and put a drop in the shaft key way, insert key and let dry. This is VERY helpful when replacing the magnet key. More gear pullers will be destroyed because the tool is not seated properly and when removing the gear you strip the threads in the tool rather then the gear as the pulled is softer.
This is the voice of experience. On these motors all of the keys are little half moon shaped things. All the shafts are straight with no tapers. If you install the gear on the shaft without the key, it just slides on, but when the key is in place, it tends to shift position and start binding as you try to slide the gear on.
If you have trouble getting the gear on all the way that's probably what's happening.