I understand this gun is "in the shop"; so I don't know if that means you are a gunsmith or not, if so I'm obviously not qualified to provide any direction. However, at the risk of personal embarassment by revealing my ignorance, you are obviously aware that there is a raised device at the base of a manual extractor iron that, that when the gun is opened, makes contact with the end of the extractor rod, pushing the extractor rod upwards and raising shell rims as the barrels are lowered. First, I would remove fore arm wood and check this raised device first to see if it has become misaligned, or bent in some fashion so that it can no longer function properly. In fact, with the wood removed, reattach the iron and open the gun a few times; sometimes a problem can be easily seen when not concealed. Other possibilities, check the "J" shaped foreiron fastener (assuming this gun has the Baker type and not the Curtis type fastener) to insure the iron is being held snugly against the knuckle of the frame so that these parts are in proper contact. You also did not say if this gun is of a regular or featherweight frame size; if it is a regular frame gun and the extractor was replaced with an extractor from a featherweight gun, the FW extractor rod would not be long enough for an R framed gun. Finally, if everything is found to be normal, the only other possibility is wear (and this problem would represent a lot of wear!). Impacted parts can be restored with judicous tig welds, then carefully filed to the correct tolerances. Good luck