This is straining the memory brain cells here but I had a Whitetail (very similar to your bow). It had 3 holes that you could use to adjust the draw weight. Seems to me it was on the 2 idler wheel arms and you put the idler wheels in the desired holes. I believe it gave you a 10# range. Don't know if the Blacktail was set up the same but take a look.
Bear Grizzly, Easton XX75 Legacy
Black & Pink package for the Princess: Martin Mystic, Sword Apex, Limb Driver