click here :
http://goo.gl/Zky7Rj

I just purchased a Toro 1800 and after reading the reviews on it, I could see why a lot of folks were complaining that the chute hood would not keep its height throw adjustment. What I did was take a Dremel tool, attach a cutting wheel to it and cut a slot on the head of the smooth carriage bolt right in the middle of it. Just deep enough so you could fit a short/wide flathead screwdriver into it. Then while holding the screwdriver in place you can use a open ended wrench or socket wrench to tighten the lock nut really tight. Works great!