nope, only options you can effect coinage in service menu is
2 credit start (premium start) yes/no
and free play.
i guess it's possible there is no adjustments to coin/credit
but there is a menu that says 1 coin / 1 credit, it's just not adjustable, it's where you would flip free play on/off
i could not find a manual for the game.
found another bug, there is volume adjustment in service menu (0-255) but it has no effect on the sound volume in mame, even when doing a hard reset (f3+shift).