Many pinballs have a coil which knocks a plunger against the cabinet to make a loud "crack" noise when a replay is achieved.
Stern did away with the physical knocker mechanism at some stage and now use a "shriek" sound in the game code.
Should be easy enough to verify if this is your situation or not by either; Taking off glass and start a game and keep tripping switches until you reach replay score; or set replay to a very low level from the adjustments menu and play till you reach the required score.
Do you have a Manual for the game?
If not, a copy is available online from
here.
