Snow thrower keeps breqaking drive belts

Question

the drive belt for the thrower mechanism keeps breaking sometimes as quickly as 2 passes down the driveway. its a 5 year old sears 5.5 hp model. the cables on the handle bars are extremely loose ? i need to know how to properly adjust the cable and what is causing the belts to keep breaking. sears sends two belts with an order for one, they must know something about why the belts keep breaking???