I have a 790 that has 400 hours on it. I bought it in 2012 new.
Last year the left front wheel sheared the drive gear at the wheel and the left wheel actually fell off as it broke the retainer clip also. I was back-blading sand and it made no sense. I assumed it was a manufacturer defect until I read this.
Just two days ago hauling drain rock the right wheel started clicking. I tore it apart to find three teeth sheered off the gear. The gears can not handle the load of having weight in the bucket while in 4-wheel drive.