I just did this adjustment this weekend... Holy cow what a difference!

No need to remove the fan shroud. I doubled-up (end to end) two combination wrenches to make a long, almost 2 ft long box wrench. Worked like a charm. I only had to turn the center screw from about 2 o'clock to 3 o'clock until it stopped, then re-tightened the lock-nut.

VERY happy with the result of this.

Hey Jim (99VC), you may want to do this on yours. I remember it had a little slop when I owned it. VERY easy adjustment. Took about 2 minutes... most of which was getting the tools out of the box.
---JIM---