I discovered something interesting today while trying to repair broken thumb screws in my A's TC lever stops. I ground flat the broken screw so the stop would sit level on my drill press, and while doing so, I noticed that the part holding the broken screw was an insert in the aluminum stop body. Looking closer, it dawned on me that the reason for the large hole on the other side of the stop was to allow the insert to be removed with a punch. I placed the stop body over my bench vice with the vice opened enough to let the insert come out and punched it right out, removed the broken screw with vice grips , then placed the insert and stop body in the vice and pushed it back in. A small washer brazed in a screw completed my quick fix.
I looked at a Cub's stops and they appear to be made the same way, though I did not take one off to find out.