I don't have the barrel removal/replacement problem on most of my lefevers. There is one HE Grade large hook version that I do have the problem with.
Manipulation of the top lever does no good. Then I took a look at the action lugs and noticed the part that actuates the extractor was blocking the gap between the two parts of the lug.
Extending the extractor/ejector released this part which could then be pushed back toward the muzzles to open the gap so it will accept the cocking hook. Works on mine. I suspect it is a wear problem...Geo
Yes, I was almost certain that it wasn't extractors that you were pulling or messing with. Those are ejectors. Big difference! And the part that was preventing you from removing the barrels is the ejector cam, which is also in the barrel lump. When the cam doesn't easily move out of the way, it hangs up on the in-frame ejector cocking levers, and prevents removal of the barrels.
This, of course, will never be an issue with guns that do not have automatic ejectors.
As Miller says, it is usually not necessary to have the gun uncocked to remove the barrels. But if the gun is uncocked, it will very often be much easier to remove the barrels on recalcitrant guns. This is why I advised making sure it was uncocked. I'll let Marks21 explain the reason for that... since he was so certain that pulling out the "extractors" would get'er done. If he doesn't have the answer... He can always ask Dr. Bob on the Lefever forum.
I'm hoping that Miller doesn't give him any hints for awhile....