I have a 2002 exmark lazer hp. I went out and bought another exmark same size and hp. Ive noticed on my older model the bars are very touchy. I barely pull back to come to neutral and the tires will lock up to a skid and shake the mower left and right. On the newer model I do not have this problem. I do all the maintenance on my mowers just like the manuel states. The handles do not feel like they are gummed up. I did adjust the knob so the mower would track straight but it was doing this before I did the adjustment. Anyone else have this problem or any ideas on how to fix this. Its hard for the guy Im training to make straight lines if the mowers jerking all over when he is trying to stop or slow down. Thanks in advance.