Ok - here it is:
After a few cleaning sessions over as many days, alternating between Hoppe's Benchrest #9 copper solvent and two different carbon removers, she is as clean as she is gonna get.
I have come to the conclusion that the rough spot I was feeling (and still do to some degree) is the gas port. I guess it should have occurred to me sooner, but I am glad to come to some conclusion at any rate. At least I can justify an end to the cleaning!
I am convinced also that there was a lot of carbon and copper build up around the gas port and all the cleaning I have done is well worth the effort. I have never had a problem cycling ammo in my Rem M742 and probably never will hereafter!
Lesson to me and others - posting your gun model is probably a good idea no matter what. Any of the experts may have pointed out the gas port as a possibility if I had thought it important to add my gun model at the very beginning of the thread.
Save your criticism for the Rem M742. I have had mine for a decade and have killed white tail, black tail, mule deer, antelope and other unfortunate critters without a hiccup. it's my meat gun - get over it!