feldpaum

I have had this snowblower for 6 plus years and have no real problems till know.   I believe that the worm drive is out in the front, when I put it in snow it goes good then it will plug up, and the front auger don't turn and the second stage blower will keep spinning.   Then all of a sudden I can tell when the front grabs and cleans out, so I'm almost sure it is in the front gear box.     My question is has any one ever replaced it and how hard is it going to be, how hard is going to be to find parts and around how much is going to be worth, is it worth doing?