I have the Williams Line Drive pinball. I have had it several years. I have a problem with the base runners hanging up. It seems to hang when a runner goes to third. I can cut the machine off, go to the back and manually back up the mechanism that holds the runners and it unlocks. I restart the machine and everything is fine but it locks up again. Any ideas as to how to fix. As you can tell I am not very knowledgeable as how to fix but I am fairly handy with expert guidance.