An easy way to gain some power in the flippers without exchanging the coils is to loosen the flipper return springs. They are sometimes absorbing a lot of power. They are secured to the bushing and you can "loosen" them by 1/3rd, 2/3rd or a whole turn...as long as the bat is returning properly of course. It doesn't count for the latest EM games like Bronco where the newer flippermechanisms are used.