I have a 7 year old Hustler Fastrak 52" and I can't seem to figure out my current issue. When I engage the deck the whole deck shakes violently and after while the belt will slip or the spring come off. Here's what I've tried: 1) I changed blades thinking one of my old blades was out of balance. 2) I've cleaned around all the pulley wheels and made sure that they all spin freely and that belt is sound and in good contact with them. 3) I've tried both loosening and tightening the deck spring. (On the loosest setting it is at the recommended length of 7.5" so it is not over stretched). When this first happened by deck support rods broke so those are also brand new. Any other ideas of what I might try?