I have a customer with a new Super Z 31hp kaw 60" purchased in March of this year. At 22 hrs the drive belt broke and we replace the belt and looked for a cause and could not find one. At 52 hrs the belt broke again, at this time the customer thought it may have been the mowing conditions he was in that time. The 3rd belt was today at 163 hrs. I cannot find anything on the machine that is wrong. Any suggestions or problems with this particular machine? We have sold well over 200 machines and rarely have a drive belt break.