Playing with the CAD model a bit I can see where the spacer would be needed on the output shaft. That end of the output shaft (between the last gear and the inside of the plate) is a 1/2" hex on both versions of the output shaft.
I would imagine that a washer with a round hole would function and that you don't need to match the hex shape to get this right. I will be stopping at the hardware store tonight and hoping that our NANO order is in today
As far as the sticky CIM pinions I can say that we observed that on one pinion from the KOP this year. It was not very bad and wore in quickly running the transmission on a bench. I can see how a small variation here would quickly cause a problem.
Rob