This can be one of many things. A dirty/misadjusted motor switch, the assembly being sloppy, or the elongated outhole.
One cure for the outhole issue is removing the trough the ball runs up and adding a switch blade below, secured by the screw closest to the hole in the trough when you replace it, then bent 90 degrees inside the hole. That forces the ball to sit properly and eliminates the real issue, which is the ball is hitting the underside of the apron before it comes up the ramp, and it doesn't have enough momentum to climb the ramp.
This problem is unique to Gottlieb. Williams and Bally used and different design of outhole kicker and I've never had an issue with either of them.