With the battery door open, put a conductor, (e.g. screwdriver or knife tip), across the 2 clip connectors on the bottom of the switch. If the laser now works the switch is defective or intermittent.
The switch can be easily removed by pulling off the wire clips and removing the nut holding it in. Look for a replacement momentary-on push button switch, that fits the hole.
Perhaps the gamemaker would supply it to you.
Or try getting some spray silicone lubricant dripped into the switch from the top side. This might get rid of corrosion inside.
My thoughts. Hope that helps.
Thanks, I will try this. The symptoms are consistent with a bad switch as there is simply no response from that laser. Unfortunately I would assume that the game is far out of warranty as I was an early adopter. It is just a bit frustrating that I have not had an opportunity to play with my recently purchased beam splitters!