Getting Beast Busters to work in MAME 0.125

[majinbuu]

No matter what I try I can't seem to get this game to work properly. I am using the mouse as the gun and need help calibrating it because on default settings the aim is way off with the onscreen crosshair. If you fiddle with the dipswitches you can enter a service mode to calibrate the gun, but then I am at a loss as to how to get out of the service mode without exiting and restarting the game.

 

Help please