Maybe the plunger/coil bracket slipped down a little ? If too low on the ball trough, it won't kick balls up. If a tiny bit too high the plunger tip will trap the balls. There are four screws in elongated holes on the end of the ball trough to adjust it.
Also be sure the rubber grommet is at the bottom of the assembly where the plunger rests. If the plunger is too low in the coil it won't get a full whack.
LTG : )