I'd start by taking both barrels off, inserting a mix of live shells and spent hulls and upending them, to see if they drop free equally. Sounds like a good chamber polishing job may be in order (I do this even on properly functioning 1100/870's). If it's old and well used, I've heard of people replacing the ejector and ejector spring but never had to go that far myself.
ETA: I'm not a gunsmith.
Last edited by InternetGuru; 08/23/16.
