Update 3 -- CAUTION, the rest of the story!
... the disturbing thing is that nothing in the pump assembly was frozen or locked up as one would think if the drive pin had sheared. Everything was clean and shiny and showed no evidence of corrosion.
I mentioned in my prior post I thought it strange the drive pin seems to have sheared even though there was no evidence of binding in the pump itself. One would think that a sheared pin would be an indication of some sort of lock-up or excess friction in the driven system.
For that reason, I took some time with close up magnifiers on to look at the evidence in more detail and am glad I did. There is a clear indication that the source of the failure in my version 2 pump after 650 hours was material related wear and not a result of overload. This is a design and manufacturing issue.
This is looking into the pump gear assembly. The circular item in the center is the motor shaft that has a drive pin through it. This pin is supposed to engage with the two U-shaped cutouts seen in the inner gear. A close look reveals that pin is not visible in the cutouts because it has been worn down to the outside diameter of the motor shaft.
Another view of both the inner and outer gears along with the motor shaft and drive pin after removal from the pump. Note the two U-shaped cutouts in the inner (driven) gear and the worn down pin that is supposed to protrude into them.
This is the close up view of the inner gear that I did not see previously. Note the gouged out section of the gear adjacent to the U shaped cutout on the far side. The near side U is similar. It is obvious from this photo and the one of the worn drive pin that over time the pin and gear it drives have not had a happy existence. The pin wore the gear and the gear wore the pin, ultimately resulting in failure of the motor to drive the pump because there was no remaining engagement between pin and gear. Unless this issue has been addressed in one of the updated pump versions, the same failure mechanism will likely occur in every pump. Again, this is a version 2 pump, purchased new with the kit in 2014 or 2015. I understand version 7 is current.
FWIW, I have opted not to either have this pump repaired or buy a new Andair pump. Instead, I ordered one from Airflow Performance and will install that instead.