Quoted from KingBW:
I fixed mine a long time ago ... well fixed it 99% of the time. I unscrewed one of the bottom ramp screws to completely flatten the ramp transition with the metal piece. That fixed it for me. Try it. Someone suggested it to me about a year or so ago and is probably buried somewhere in one of these WOZ threads. Remove one of the screws and see if it helps. If not, switch to the other screw. If that still doesn't work, at least you tried something that worked for a few people.
While I don't have many ramp airballs, it would be nice to have zero. I tried removing each screw & then both screws but could see no change in how the ramp or flap were positioned. Even with those 2 screws removed, I could not pull up on the plastic ramp--it's secured well by other fasteners.
What I *did* notice was that my steel flap was pulled away from the wood playfield juuuust a little on the right side (near the rainbow targets). May be a non-issue, but I didn't see a way to tweak the flap down without pulling the whole ramp.