Problem is that the ball doesn't rest on the plunger, the plunger tip is about 1/4" below ball, and slightly off center towards the rear of the scoop. Between those 2 things and the play between the plunger and coil sleeve (which is obviously necessary) it's creating a random shot out of the scoop each time.
Since last night's post, I taped some shims between bottom of plunger and rubber grommet so that tip of plunger is higher, and ball is resting on it every single time. I threw the ball in the scoop by hand 50 times in a row and it came back to the same spot on left flipper nearly everytime. It didn't drain once. I then put the glass back on and played 3 games, aiming for scoop as much as possible- not a single drain.