I like pinball life personally. Use the little spring that hangs off the metal tab on the side for the return spring, throw the big cone shaped spring that goes over the plunger away. Keeps them from jamming and returns a bit faster. Other than that, really crank down the screw holding the flipper bat real hard so it doesn't move from the vibration. Blue loctite works pretty well. New EOS switches have the tendency to not make contact, clean with index card (not sand paper). They have a coating to keep from corroding and new switches might be a bit wonky. Rebuilt 10 flippers so far with new components. They definitely can change the game. New coils/sleeves work well too. Also replace the cabinet switches and filtering capacitors when you replace the rest of the flipper assembly. Keep all the components of the same age.