Ray
I believe what you said is correct. The main landing gear shaft has a flat side that the Transition gear box slides on that runs the Landing jacks up and down. There is a collar that slides on the flat shaft up against the transition gear box and has a Philips head self taping bolt that goes
through the collar and hold the transition gearbox on the main shaft. The plastic nubs straddle the jack housing. The shaft on one side extends to the outside which is where the manual crank is attached through a hole in the side of the hydraulic cabinet.
The Motor and the square gearbox is one unit. Two bolts hold the motor to the square gearbox and two long bolts mount the motor and the housing to the transition gearbox.
Now in my opinion this is quite a jury rig. I would like to see a way to turn the main gears with the manual handle. It might be a hard job with out the transition gearbox. Dave at Lippert told me if I have to use the manual crank it would much easier to remove the motor from the transition gearbox before raising or lowering the jacks with the manual crank.
That may be why the plastic nub broke off. There is a brass pin part way through the plastic nubs.
By the way, Kenny, the tech that came out and replaced the gears told me the bolt that goes through the shaft is a grade 5, 1 inch long, 1/4" bolt. He told me not to put a grade 8 bolt in place of the grade 5. You may bend the shaft rather than break the bolt.
Another thing I found out from Dave at Lippert. If you can't use the manual crank for some reason take a large crescent wrench and turn the horizontal shaft. Might take a lot of half or quarter turns but it will raise or lower the jacks. Probably be easier if the motor is removed.
Hope this helps..