We are all struggling with the Success rate for launch of the ball, and there are a few things folks have tried to help. The washer trick is one of the most successful mods which seems to help.
Related, I think Stern knew this area was a problem as theY mysteriously ship all machines with a weaker GREEN spring, rather that the ORANGE one in their specification. I can’t help but believe that they tried to increase ball launch success by removing some of the power of the shooter.
Or just coincidence?