Quoted from Chosen_S:I don't like the system 11 kits, I get the wpc ones for all my system 11 games, they've always worked great and the Spring action is nicer imo
That is the problem. The plunger length is different between the two eras, and is why your flippers don't look right when up. You can retrofit wpc style return springs onto system 11 kits, but they aren't 1 to 1 replacement.