I have an 03 Exmark Z turn hp. I love this machine, and have never had any problems with it untill now. But I went to run the machine and get it ready for the spring and the throttle won't stay all the way down. (the throttle is on th front of the mower, not up on the gas tank.)It seems to be loose and while it will go full throttle, within a couple of minutes it works itself to about half throttle. Anyone else have this problem or have any idea how to fix it? Any imput would be great.