I have been having a problem with my sanding belts breaking within a couple of minutes of use. Even the new ones I bought at the store were breaking soon after I started using them. I went through four belts in about five minutes while sanding the planer marks out of my cabinet door today. I was not applying any pressure on the belt other than the weight of the hand-held sander and I wasn't hitting any edges.
I read this Belt sanding belt joints post to see why my sander belts are breaking so quickly and concluded that it is because the belts are old, even though they have not yet been used. The sander is an old (40+years) Craftsman, hand-held, 3" belt sander. My neighbor suggested that the belt tension may be too tight. I'll have to look to see if there is an adjustment for that.
Is there a way to tell at the store whether the belts are old and have been on the shelf a long time, and is there a trick I can use to keep them from breaking so soon?