The problem I am having with the sander is the belt portion. It won't stay on track. If I don't use it, it will stay for about 2 minutes, but as soon as I start sanding it will instanly start to go up or down. I have checked everything. I know nothing can be wore out. It has really done it ever since I bought it about 2 years ago. Other than that its a good little machine. Anybody have this problem or know what to look for or any ideas. Thanks for any info.