I say go the opposite way and set the tilts up tighter on the modern games to match the EMs. It sounds like you have people manhandling your games, which a lot of operators would consider "unacceptable" in their arcades.
Make the plumb bobs fairly tight on all the games, and reduce the tilt warnings to 1 or zero on the modern games.
Start requiring your players to use skill and finesse (and more careful nudging) rather than ham-slamming the cabinets and leg-sliding the games.