I did a search for z-truck bearings to see if I could find out how long they were supposed to last, yesterday I was doing a ! hour carve and towards the end I heard a much louder ( scream for lack of a better word) coming from what appeared to be the area of the z-truck, I also felt the machine and it had a little higher vibration than it normally has. I think its the bearings inside the z-truck are starting to go. I turned the machine off right away. and have been trying to find some information about it ever since, under search I only found two references, but neither apply to my problem??