Quoted from Chambahz:A very common issue with AC/DC is the LEDs popping out. If one rolls down the PF and into the ball trough, it can block the balls from flowing through properly. Check to see if any of your LEDs are missing (under the lower slingshots and the 3 above/behind the lightning bolts).
If that's the case, it's an easy fix.
Good luck!
Also behind the T.N.T targets