OK, I think I have it sorted out. Those telling me that the problem was the trigger plate being too high into the sears were correct. The screws weren't tight this time, but I might have torqued them up when I had it open before and deepened the inletting. It was easy to see what was causing it when I assembled the gun without the stock on. I fired about 2 boxes of shells from it today and all seems well.
Thanks for the help,
CHAZ