Oh WOW! You have a job on your hands I am very sorry to say.
Been there. Done that a few times now. My system is different only in that I have a motor for each leg. I also have a genny enclosure to contend with but there is enough space between enclosure top & basement top for me to lay on & reach the leg.
There really is no other way of working on those legs without removing them. Too many bits, like a gear shear pin to lose down the leg casing.
You can either remove the genny & its enclosure or, & I think this is the way I'd do it, create an access hatch for service. Look up deck hatches or access hatches in a place like Defender.com They have Bomar inspection hatches in various sizes. It does not need to be lockable but you do want it weatherproof. Be sure to get the largest one that will fit so that there is working room to get arms in there.
The leg will need come out somehow. The usual way is for it to come out from the inside. Think about that when choosing hatch size otherwise you may still find yourself removing genny & enclosure to gain room to move the leg.
Gotta love RV builders. They don't have to deal with their products when things go wrong.
Not related to the gear problems but I see another problem waiting to happen. Chafe. The white wires resting on the link shaft are destined to wear through & short if you don't get them clear of the shaft.
