Take a picture of your setup from this angle please. Does your 00-50 collar have a cutout relief area like mine(just above the handle in my pic) the manual doesn't show the cutout I have, maybe mine has been modified or the manual isn't accurate on that part, since it shows the pin. Anyway to see where the pin is at, you would need a mirror, or remove it to see where it's located, if yours is built the same way, and mine wasn't modified at some point. The pin is suppose to be in the 382-039 "lock anchor hub" you don't have to disassemble the assembly to see where it goes. It's external on the lock anchor hub. My serial number 601610 so it should be the same according to manual, unless this was a "fix" at some point in it's lifetime.