Quoted from pinballinreno:
Widening the prongs that stick out at the bottom of the loop 1/8" (basically widen the loop at the bottom) and bending the loop up about 3/16" to 1/4" will have a positive effect without grinding. this allows the ball to duck under the loop.
I havent had a game in my collection yet that didnt need tweaking of the wireforms.
(Remember On the TZ we all gave up fixes and added a magnet to the diverter).
Most games need a little quality time to get them close to perfect and somewhat reliable.
I expect JJP games to be no differet
The HUGE difference is the way that games are supported during warranty, and after.
The team at JJP is incredible!
Please note, I was referring to Luke's specific wireform. The photos below, taken from Luke's video, show exactly what I was referencing.
The two nubs on the left and right of the wireform rails are just slight extensions from the vertical wires spot-welded to the loop, and on Luke's machine, they are actually tipped upwards, causing the ball to ski-jump up and over the loop. That particular problem, which is pretty common -- spot-welded wireform parts don't typically have very tight tolerances -- can easily be fixed in less than 15 minutes with a Dremel rotary tool. Just cut or grind down to the blue lines on the magnified mark-up in the lower photo.
Installation of the post on the left will prevent balls skipping off the wireform rails and passing the loop on the left hand side. Bending the loop up slightly with pliers will increase the likelihood that balls will pass through the loop instead of skip over the top.
Just a little added TLC for a hand-built machine. Nothing radical. This is a classic example of tweaking the gameplay on a pinball machine.