Skil Belt Sander Problem

My Skil 3" x 18" belt sander suddenly lost it's ability to track well. It happened all of the sudden. The tracking control no longer seems to function. Any advice?
Thanks, Richard Green
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.