Quoted from javagrind888:
Ok, so now I'm at a complete loss on the auto launcher. I've put washers on the plunger to pull it back further away, re-situated the auto housing, zip tied the coil, put a washer in so that it doesn't wiggle as much, tested the range of strength settings, and crimped the prongs to be closer together. There's no reason this shouldn't be working. It seems to get worse the more games we play on it in a row.
I had autoplunger woes as well that I have finally fixed 100 percent. It is perfect now.
I tried all the steps you did. When it would fail, the ball was striking the wall or the locker post and losing energy.
In my case the fix was adjusting the shooter lane rails. There was a slight discrepancy between the left and right rails which gave it just enough lift on one side to launch left or right.
Interestingly, only the autoplunger failed in this way. Manual plunges were fine.
There is a post in the index for how I removed and corrected my shooter lane, if that is your issue.
Another thing to confirm is that the auto plunger is not making contact with the manual plunger. If you snap it empty do you see the autoplunger forks jump? If so, you’ll want to adjust the shooter assembly to be further down the cabinet. If that doesn’t work, consider adding cabinet bumpers under the playfield hooks. You’ll need to relevel after doing this of course.
The combination of these two fixes fully resolved the issue for me.