It's super-easy to re-face the armature plate with a grinding attachment on a Dremel tool. It takes about 5 seconds to smooth out the plate, even when there is a fairly deep divot in it. I use a #455 grinding stone.

You don't even need to take the relay armature off. Just remove the coil from the relay frame, and re-face the armature plate in place. I also run a wire wheel attached to my cordless drill over the face of the coil core while the coil is out, to remove tarnish and burrs from the coil core.

I've done this on thousands of type AG and type R relays while rebuilding Gottlieb games, and it works great.

- TimMe