Quoted from nodyeliab:
I was having the same problem a lot of others were having with the ball bouncing out of the left ramp exit.
Anyone curious to the exact cause I've illustrated the issue. The top (ball stopping) part of the wireform on the "bad" ones is parallel or worse slightly further toward the player than the bottom (ball dropping) part. This causes the ball to ramp upwards and go flying. I've illustrated (poorly) the part that is angled in on the newer correct wireforms, which causes the ball to immediately collapse down through the hole. You'll see on his original direct overhead shot a few posts up how the top is clearly further towards the player than the bottom. This is the manufacturing error.
Fixing this is not a matter of just bending that thin piece I'm pointing the arrow at so the top is before the bottom, since these pieces are connected at other thicker points along the way. But if you have access to tools that allow you to make this happen, you'll have fixed the issue.
On proper wireforms, the ball should NOT bounce back at all when it hits the end of the wireform, it should immediately drop down.