Before working on the coil, I replaced the coil sleeve, made sure there was no slop in the plunger and that everything on the coil was tight and that the ball was being struck in the center by the plunger. (I adjusted it to center and it helped a little)
With the standard 23-800 coil the ball landed in the pop area about 20% of the time.
Removing 100 rounds of the winding (23-700) the ball landed in the pop area about 70% of the time. (big improvement)
Removing another 100 rounds of the winding (23-600) the ball landed in the pop area about 90% of the time.
I would be afraid to try 23-500 because occasionally the ball actually lands all the way across the pop area but usually it just glances the top of the first plastic or bounces off the edge of the left pop bumper.
I printed up a 23-600 label so I don't forget what the coil is... hope this helps