Yakima Flipside Bike Rack arms will not lock in upright position?

Recently got a bike rack from a friend and the arms will not lock in the upright position. I disassembled it and it's just not very clear how the mechanism works when the arms are raised. I am enclosing a few pictures (with the cover removed for clarity). I was unable to obtain any sort of manual or diagram from Yakima. To their credit, they have lifetime warranty for the original owner and they would simply have replaced the rack, but I am not the original owner and my friend does not have the proof of purchase info.

If anyone has a Flipside or a Doubledown hitch mounted rack, I would greatly appreciate any photo's of the internal mechanism in the arms fully extended position. You will need to remove the plastic cover on the mechanism (quick job, requires removing two allen head screws). I am attaching a few pics of my rack with the arms DOWN and UP. It looks to me that there is a piece missing, but without a manual or detailed drawing, it's hard to say for sure!

Thanks in advance.

Arms Down. This works fine

Partially Extended

Arms Fully Extended, View of Latch Mechanism