First thing first. Please do not respond with questions or comments until I have completed this, and there are about 15 pictures and some commentary.
By not interrupting the flow, it will make it easier for others to follow this procedure if they ever have to replace a motor.
Before I get into that, some general thoughts on the Az Mount Pro design and engineering.
I greatly admire the design of this mount. It is compact and well laid out. All of the materials appear to be good quality. The circuit board has good packaging and is well finished.
The mount is mechanically a beautiful piece of work. The biggest upgrade vs the MiniTower pro is the azimuth axle bearing. The Minitower Pro used small needle bearings. This mount uses a large tapered bearing. This bearing is by itself able to easily support the payload rating of the mount by a factor of 3 or 4 times. This would be the size bearing you might expect to see on a golf car front axle. For this reason, there should be zero concern about having perfect balance in azimuth. The bearing is absolutely oversized for any load that you could put on it up to the load rating. Why people obsess over the need to perfectly balance this mount is beyond me. Previous to this Az Mount Pro, I had another one, and I ran my 8" f/2.8 scope on it whiteout a counterweight with no problems. The only reason why azimuth balance would be important is if the mount is not level or the tripod is deflecting and the motor stalls when it has to push the off balance weight up hill. The Altitude balance would be more important and here, I would say that you want to be somewhat close.
The motor mounting is elegant but unnecessarily complex. I will get to that when I am doing the photos.
About belt skipping. I have heard people say that they heard the belt cogging. I can just about totally assure you that this is not happening. If you hear a sound like a belt cogging what you are hearing is the worm gear teeth being deflected out of the worm wheel and the rapid RumpRumpRump is the sound of the teeth on the worm gear skipping across the teeth of the worm wheel. This is from insufficient tension on the spring that holds the worm gear in mesh. This spring should be kept fairly tight. I would say that one turn from motor stall is about as much as you should allow. If you go to far, if you are out of balance in DEC or you bump the mount in Az and it skips, you can damage the worm gear.
I have to resize every picture so I might not finish this today or even tomorrow, but I will get started today.
Again, please hold comments or questions so that the flow is un-interrupted. If you have a burning question, please PM me.