Hi, I'm new here and I've been looking through the old articles and all over for info that explains this clearly but I have found nothing that I can make any sense of it. The serial number on this motor is 0D018122. It is a 25hp. Can anybody tell me what year this is so I can get the right repair manual. I am try to see how to adjust the cam that is part of the throttle linkage. Does the arrow on this particular cam point somewhere? Thank you in advance.