The lamp flasher board drives the flashers and you have replaced it. The flasher bulbs ar 12v automotive lamps so yep there are 4 in series so they can run off of the 43v coil power.

The flasher board should have a load lamp nearby that allows it to be controlled by a lamp board SCR. The load lamp is often missing or accidently replaced with an LED. Check that first. It should flash when the game is in lamp test. Most times when these aux boards are not working it's a problem with a board connection or with the load lamp.