Is the ball hitting the pin and jumping over or pushing the pin down and rolling through? The pin should be held up by a spring and when the solenoid engages it will pull the pin down. If the spring is worn and has lost it's tension the ball could force it down. It could also be an angle issue, I believe Street Fighter is supposed to be around 6-6.5 degrees. You can test that quickly by putting something under the front legs to lessen the angle and see if you still have the problem.