Here is something additional to note. We just replaced the "cam followers" on my 1660 these are the "rollers with the grease zerks" on top. If they are woren a little flat on one side or another it will not tighten down on the belt and will stick open and the belt will get pulled into the bottom of the driven pulley and will cause failer to the belt. requires more time to tell you about . Latter. hammer