Quoted from Solder_Splash:

Here's the design issue with Lightning (more of a software flaw).
When multiball is achieved balls are re-locked if you hit them back into either of the kick out holes on the upper playfield.
So quite often multiball ends when you re-lock the balls versus draining them.
Very frustrating to achieve multiball to have it immediately end by re locking two balls.
It should have been coded to eject balls instead of re locking them.
Besides my lack of room, this was one of the main reasons this game wasn't a keeper for me.