Oh gosh, I&#039;ve run into this before. Let&#039;s see, as I recall there is a mark on the timing gear, I was working on one of the first ones produced, and I think there was something strange about it, different from later models. I really need to have your serial #, that way I won&#039;t tell you something that will get you hurt. The first ones are much more difficult and complicated, compared to the later ones.