rivet tool

I have a 628 44 ton switcher, and I'm having a problem with the couplers letting go and the engine shooting off on it's own. I've looked them over, and I kinda' see the issue, the coupler magnetic release is separate from the actual coupler, and when the coupler flexes up and down, it actually...

Anyone have a source for coupler parts and some hints on repair? My current method is to carefully drill the bottom of the pin to remove the knuckle, that works, but I don't have replacement pins. I have some of the plastic ones that have lost their "spring", so I'd like to find a source of...