Winchester Mod. 21 ejector problem

[David Noble]

I sold off a Model 21 about 25 years ago and do not remember how it normally extracted and ejected shells. I recently acquired a Model 21 12ga with an ejector problem. I'll try to explain. When you open the barrels (whether there are shells in the chamber or not) the extractors lift to their full extent and you can feel the ejector hammer springs pushing against the extractors. If you fire one side, it will lift the unfired shell all the way up and eject the fired round when it hits the trip. In other words the extractor blades will both then be fully extended. This may all be normal operation, I can't remember.
My problem is the ejector hammers will always trip when the forend is removed if the gun's hammers are cocked when I remove the forend. It is fruitless trying to install the forend until the ejector hammers have been manually reset. I have to push the ejector hammers back and manually operate the sears in the forend to lock the hammers back. This is pretty tough to do! Now, if I fire both barrels but do not open the gun, the forend will come off in the normal fashion with the ejector hammers locked back. However, once removed it cannot be reattached until the hammers in the action have been manually recocked. That is a bit easier than cocking the ejector hammers, and once this is done the forend will snap right on. But as soon as you open the action its back to square one. Obviously the sears are not properly engaging the ejector hammers when the gun is closed. But why are they engaged if you fire both barrels, (but not opening the action) and then remove the forend?
Has anyone ever experienced this problem? Any suggestions?