just unsolder and solder in a new one, pay attention to the direction of the "anvil" so you get the polarity correct. had to replace several of them in a couple zizzles. "anvil" being the shape of the metal inside the LED itself, kinda |_/| , if you look very closely. 5mm water clear wide angle (x-color) if you can get them, but the dome tops are ok too. find them ebay or amazon.
a little easier said than done, they dont give much of anything for wire length. I've snipped them, stripped them 1/8" to solder connect back in and a dab of hot glue to re-insulate it.
http://www.amazon.com/250V-Momentary-Button-Orange-Arcade/dp/B008MU2THC/ref=sr_1_4
http://www.amazon.com/Arcade-Games-250V-Momentary-Button/dp/B008MU2UWG/ref=sr_1_9
is the type arcade buttons you'll need for good fit and performance, some drilling required. theres also possibility of finding higher quality-capacity momentary switches for mounting on the existing pcb's in the stock button assemblies. wimpy flipper button switches was zizzle killer #1