Carnevil optical gun issues

[Tlongan]

I have recently purchased an original carnevil cab and everything works great except for the player 2 gun. They are not the original shotguns they are Happ 45 replacements. The player 2 gun does not fire it just reloads when pointed on and off screen. When I try to calibrate it I cannot shoot the calibration points and the reticle displayed on the screen is very unstable and jumps off the screen with the slightest movements. This is my first cab so I do not have a lot of knowledge to diagnose this issue myself please help!