I am new to pinball. Just bought a Jurassic park Lost world pin, no modifications. Most everything works, but when it enters into the two ball multi-ball modes (mobile lab and raptor) it keeps adding a ball every time one drops off. It seems almost like ball saver mode stays on but without the ball saver light staying on. It never leaves that mode and we have to turn it off to stop new balls from being added. It never goes over 2 balls in this mode. I have read some posts about other machines and endless multi-ball due to trough sensors not working properly, but this doesn't seem to apply to me since when it enters true 4-ball multi-ball I don't have the same problem. Any thoughts would be appreicated.