Got the EDC back from Camillus today. I don't know what they did but the lockup is now rock solid, locking bar 1/3 of the way across the tang, just like it should be etc. Before I sent it away the lock up was highly variable and moving all the way across to contact the opposite scale, regardless of how tight I made the pivot. It doesn't appear that they changed the stop pin either as this seems to have the same markings as before. The only thing I can think of is that the bolts holding the stop pin may have loosened. Given that this is one of three points holding the thing together, having it loose may have introduced some slight twisting which may have thrown the contact point of the locking bar out. I'm told getting this right in manufacture is a very precise art/science.
I couldn't get to tighten this myself as the allen head on the lock bar side is under the pocket clip which is held by three torx screws that I didn't have a tool for.
I'd love to know what they did but the repair slip that came back with the knife didn't elaborate.
Oz customs opened the package but didn't hold up the knife.