MCI 5C Air Wiper Motor Shaft Indexing

[Gary '79 5C]

Removed the OEM air wiper motor to rebuild same about 5 months ago. Have not been using the bus as much as we should, only short trips around the airfield..
My question is how should the shaft with arm be positioned before assembly. The Maint Manual is light on this but the diagram has the shaft arm pararell to the motor body. However this does not show nor indicate a reference to the sliding rack which drives shaft.

The manual is not exactly light,. but rather warns to note the position of rack & drive shaft, before full disassembly. I will look to reassemble tommorrow AM.

Hence I am asking da question. I just try to install and reposition the wiper arm on the post in relationship to the windshield.

I am not looking to change to electric wiper motors, just not yet.

Have a Great Independence Day Weekend !!

Thanks for consideration of this question.