Miller,
From here, listening to what you say, I'm going to go out on a limb and speculate that the spring, under the plate that raises unfired rounds from the barrels is tired in your gun.
If you remove the barrels from the gun, you can observe the operation of all the parts by just pushing the breech block up to where it joins the barrels and closing the action. You can observe how everything works in that position:



You won't need smoke, you can observe everything in that condition. Put the muzzles into a piece of carpet, line the breech up with the tubes, press the breech forward, while easing the lever closed and lifting the tab up that allows the breech block to be removed. The breech block should grab onto the barrels fairly tenaciously.
Be careful, the edges of the sliding breech are exposed in this condition. They are sharp enough to cut you. In my Halifax, the rising bolt makes contact with the L shaped lever briefly and lightly, and the spring, under that plate, is busy shoving the breech block rearward from the moment the lever is lifted out of battery. If the spring got tired, the bolt would put more force on the lever, but, I suspect that isn't how things should be. The lever, in the position I illustrated in the above photo, has perhaps 1/8th inch of wiggle room when the spring is compressed.
The lever exists to allow the gun to be properly timed, with action completely unlocking before the spring is allowed to put full pressure on the sliding breech and pushing it open.



Best,
Ted