if you have the 891-1, the payout disc will have "M-645-156 REVISED 10-4-72". Diagram below.
first thing I'd try is to find another payout disc. Barry at Fox Slots or another slot parts supplier may have that one, and there's always ebay.
an M-645-118 may work depending on the payouts needed on your game.
I don't see how the 50 pay works using the M-645-156 disc unless the upper/right CO trace is connected to the 50 pay...got pictures of your disc? Pics may not help if the magic is wiring on the back side,
anyway, if you can't find a replacement payout disc, I'd seen kludgy repairs to the traces using copper foil. Silver epoxy may also work, but is way more expensive than finding a replacement disc.
ideally you don't want to file the contacts unless they are badly pitted. Something like a flexstone or just alcohol will clean off any crud and it's the overtravel of the blades after the contacts touch that make a good mechanical connections. Make sure the switch stack screws are snugged down first, then the switch blade adjusters the pinball parts people sell make life easy.