Quoted from lodgingdolphin:

I had this same issue except well over 50% of the time the ball would hit the pop bumpers first and not reach the skill shot. I tried adjusting the plunger with only a slight variation in the amount of successful plunges. I sent photos and videos to my distributor and he suggested adjusting the outer ball guide that ends where the ball exits the shooter lane. At first I just tried bending it and that only helped slightly.
I determined that the ball guide was most likely not installed in the correct location. There are two mounting holes in the ball guide at the end where it curves. First I tried just loosening these screws and shifting the ball guide. The screws fit pretty tight in the mounting holes so I couldn't make much of an adjustment. I moved it as much as I could, but it wasn't enough. Then I decided that only way to shift the ball guide further would be to drill the ball guide mounting holes to a larger size. I hated the thought of doing this, but I hated the skill shot problem even more. I drilled out the holes and kept moving the guide, tightening the screws, and performing test plunges. It took about 5-6 tries before I finally got it into a position that worked. I did this back in February and have had a 99% plunge skill shot success rate ever since. TWDPIC.jpg