I have terrible power as noted many times on the Houdini thread.
My power goes from 113v to 124v in a single 4 hour session almost daily.
My AFMr at high voltage throws the ball around like crazy and cant even keep it on the wireform.
At low voltage the ball goes SDTM off the SOL every single time and I cant get the ball up the ramp.
One of the joy's of pinball is the "unregulated" power system in the game.
Few, if any, games have power regulation (Houdini might be the first?) to insure even, constant game-play.
So, I put it on a variac at 118 or 119v, adjusted all of the game settings and now its amazing! Super consistant and a joy to play.
My TH cant make the windlance shot consistently unless on the variac or I fiddle with game settings daily.
I just got tired of adjusting my coil settings daily, I regulated the power instead.
Stick one of those little AC outlet voltmeters in a socket on the same breaker as the game, and look at it when the game play seems off.
For me it was enlightening.