Pinball Resource shows loose switch parts including just the contacts at http://pbresource.com/pfswitch.htm (look for "Common Switch Parts" near the bottom). Or you could pick up a couple of old M relays on the EM seeking parts thread (https://pinside.com/pinball/forum/topic/the-em-seeking-parts-thread), or on ebay. Are you sure you need new contacts though? Worn contacts aren't that common.

/Mark

http://www.pbresource.com/relay-WMS.html

If you have to you might be able to file off the backs of the contacts where they've been flattened out.

But arcing between contacts is a fact of life in most EM games. If you open a switch in a circuit where there's enough current running through the coil the current will keep flowing even after the switch has opened until enough voltage has built up on one contact to jump across the air gap to the other contact - kind of like a static spark between your finger and a light switch after you've shuffled across the carpet. New contacts won't change that.

If you're familiar with capacitors and how the voltage across them can't change instantly, coils (or inductors) behave the same way with current. The current through the coil can't change instantly but needs a short period of time to increase or decrease just like the voltage on a capacitor.

Or in other words, save your money and enjoy your game until something fails.

/Mark