I have a 924312-000101ST924 blower built 2001. I live in the...

I have a 924312-000101ST924 blower built 2001. I live in the foothills outside of Denver CO. My driveway is dirt and some rock. I use factory shear bolts and keep my auger well greased. I also use a 80W-90 gear oil in the transfer case.I have broken the teeth off of 3 worm gears, the orignal plus 2 others that I bought and installed.I've replaced both the drive shaft and the worm gear.I like how this machine performes, but I can't use a machine that keeps costing me apox. $100 every time it fails.My last blower I wore out after 11 years of use. Are ther any solutions to this problem? Can I get only the worm gear if I need to make a repair.