I bought a new distributor cap, off of ebay (a red one) to replace my old cap(a black one) because it was missfiring. When I put the new one. It wouldn't run. So I put the black one back on and it wouldn't run ether. But it ran great earlier that day with the old one on (just missing a little). I don't know what I have done to it. I notice that the part from the cap that touchs the rotor button are alot diffrent in shape between the red one and black one. i need some help. thanks