Sometimes after you have done all the easy stuff move to other points 4 ought steel wool and gun oil on a 20 ga brush in the tip section of your cleaning rod. Chuck it up in your rechargeable drill and clean and polish the chamber. How long has it been since you pulled the butt stock off and pulled out the recoil spring from its housing and cleaned both ?
I was going to suggest BOTH of these options... do it and the gun cannot help but run.
