It sounds like you're already barking up the right tree, but just in case you need to keep digging never underestimate the power of putting the game in switch test, closing the coin door and hitting the flippers for awhile. If you really want to work on your coordination try it with a ball as well (an assistant to watch the switch test display on the DMD can help here quite a bit as well). Obviously pay special attention to the trough switches and the long range opto on the matrix.