I have a Sears 20GA simi-auto shotgun that I've have had common ejector jamming from day one. Taking a close look at it, the ejector bar starts to push the casing out when the shell is already a half inch inside of the ejector opening. This pretty much just bounces it back into the chamber and the next round traps it. Seems to me the ejector should start while the casing still has a clear shot though the opening. I have it all apart now and there is nothing broken or missing. Short of getting a new gun, what kind of mods would be recommended?