You may want to talk to one of the gunsmiths that have been recommended by Walter Snyder, a couple of which worked for Ithaca for many years. One he suggested to me for my Knick is: Gunter Pfrommer, 540-484-5555 and the other is Les at: repair@diamondgunsmithing.com. I bet that one or both of these gentlemen will be able to help you, they may even have the part you seek.
My Knick has an ejector problem also, the ejector kicks every time, whether the trigger was pulled or not. Other than that, the damned thing is a laser on the trap range. Hit 28 out of 30 the first time I took it out and when it hit them it smoked 'em! The two misses I can 100% attribute to brain fade on the part of the operator.
