They are a 555. I've fitted one already and it's not working but because nothing was working when I got this machine I'm unsure if it's the holder that's the problem or something else. I swapped the spoon switch at the same time and the bumper is working just not the globe. I have tried a different globe in it as well just be be sure it wasn't the globe. The boards have been rebuilt and all .100 and .156 connectors have been re-pinned throughout the game. All other lights are working.