Lloyd, I'm well aware of your expertise, and I have a lot of respect for you. I appreciate the diagram. I understood what you were suggesting. In the interest of trying to be more clear as well, I will explain why I am saying this fix is not going to work. If you don't agree with my assessment, that's fine.
Look at the picture of the two Bally relays. The one on the left has no clip or spring. The one on the right has both a clip and a spring.
bally relays (resized).jpg
Look at the red arrows on the left relay. They are pointing to the two very short shoulder tabs that keep the fulcrum end of the armature in position on the relay frame. Now, on a different style of relay (like a Gottlieb AG relay) these tabs would be much longer, and in that case, the pressure of the return spring holding the fulcrum end of the armature against the frame would be enough to prevent the armature from jumping off the shoulder tabs during relay operation.
Looking at the relay on the right, you can see the green arrow is pointing at the bent tab or tongue on the front edge of the clip, which is retaining the fulcrum end of the armature such that it cannot jump off the shoulder tabs. So, what I have been trying to say is that, without the retainer that is built into the clip, the return spring pressure alone won't be enough to prevent the armature from jumping off the frame during operation. You can certainly make the case that the spring, all by itself, will take care of keeping the armature in place, but I believe that the Bally engineers put that retainer on the clip for exactly this reason.
As to why the tabs on this style of relay are so short, I don't really know. My guess is that they are short to allow for easy removal of the armature from the relay. As you know, you need to rotate the armature out from the fulcrum end to free the two bent metal tabs sticking though the slots on the plastic actuator in order to remove the armature. I suppose that having longer shoulder tabs would make it more cumbersome to do this, but as I said, that's just a guess.
Thanks - TimMe