Kutter..."been there, done that". I can't send it back a third time to the same person. It's becoming very expensive with little hope of a different outcome.
I had a gun that functioned perfectly with very heavy trigger pulls and now I have a gun that works most of the time with lighter pulls. Neither of these scenarios is very attractive.
Your hypothesis is one of a couple that were discussed and looked into.
My gunsmith is a very knowledgeable fellow but, obviously, not an expert on this gun and its trigger. At this point, I want someone who is.