David you might have an alignment problem where one or both of the barrel channels is forcing the forend out of alignment with the ejector mechanism (the real name escapes me at the moment)in the frame. You might put some black on the barrels to see if you get a rub mark in the barrel channels but if the ejector activates when it is tripped with the forend removed I would say that the alighment of the forend is probably your problem. .