Quoted from Jenniebear:I had the same issue with pop bumpers from Marco’s. I had to take everything back apart and replace with pinball life ones.
I had the same thing happen in my MM, no amount of adjusting or bending the rings would stop it and I had to re-do the whole process with different bodies. I think I ended up with bodies from PBR though. http://www.pbresource.com/pfbumpb.htm