So my friend and I both have Iron Maiden pros and we are experiencing the same issue with the lower right flipper getting progressively weaker with longer game play. It gets to the point that you can no longer hit the bullseye target behind the center ramp flap (the ball will barely clear the ramp itself). Looking through the settings, there's nothing to really control flipper power directly, and the generic setting that is there is already "maxed out".
These games are too new to have typical "wear" issues that would cause weakness (dirty coil sleeve, mushroomed plunger, mushroomed/broken coil stop), and the EOS switch is properly adjusted (even it's not really used in that capacity).
To complicate matters more, played a mutual friend #3's IM Pro last night. His flipper strength was stronger on all 4 flippers and never lost strength. He said he didn't touch any of the settings either.
I realize there are subtle game to game differences on all copies of the same title, but this would be obvious to any decent player.
What is there to look at for troubleshooting here? I've got an AC/DC, MET, LOTR, TWD, Star Trek and X-Men and I've never had any issue with the flippers no making shots (either initially or after a long game).