It's not hard to poke around in. Three crosspoint screws in the mount & you can see the stop down mechanism.
Your thought about the lever pressing into the lens has a lot of merit. If I recall correctly the lever you're referring to is attached to the inside of the lens mount.
When reassembling, the stop down lever slips into a notched ring around the diaphragm and that's the only timing or alignment you need to be aware of.