No, I am not blueprinting anything. I checked today and there are indeed 4 marks on the balancer and all go all the way across.

If you view from the front of the motor starting with the mark furthest left:

1st mark is bolder (slightly wider and deeper) than the other three. Moving right there is about a 1 3/4" space until the next mark. Then about 5/8" to the next and maybe 1" to the last. (those are all guesses) I can get the exact measurements tomorrow if you think that will help. The three that are closest together are all uniformly thinner and less deep grooves.

If I had to guess, I'd say the bold line is it. I think the positive stop may be my only answer.