Quoted from JKnPA:
I would put games on the Replay Counter, worry about the coin sw. later.
just to be pedantic … 'cause everyone loves a nitpicky git ... the replay register is the unit with the numbered reels showing the credits. The replay counter is the unit that stops payout when the right number of credits are added.
on big time, there's one replay counter and it's on the top left of the lamp panel inside the head. On many later games, there's a replay counter for each color you can independently score or for every card on a multi-card machine.
if you add credits to the replay register with the power off and you don't want them removed when you turn the game on, hold down the anti-cheat relay armature/plate while turning on the game.
since big time has the older style relays with metal tab over the armature, you can stick a hunk of folded paper between the tab and armature to hold down the armature. Do it a bit loosely to avoid coil buzzing.
keeping the anti-cheat closed between power cycles is handy when working on the game. The machine will keep doing whatever it was doing when you turn the power off/on.
manually resetting the replay counter will let the game pay again, and if the timer unit steps up all the way and tilts the machine, reset the timer unit and untrip the tilt trip relay with your finger.