how do I fix my snow thrower?

I HAVE A MTD YARD MACHINE 5/24 --2 STAGE-- SNOW THROWER MODEL #313610e00 SERIAL #1L012840062. MY PROBLEM IS REPLACING THE WORM GEAR THAT DRIVES FRONT AUGER. THE AUGER TURNS FREELY AND SHEER PINS ARE INTACT. CAN I STILL GET A REPLACEMENT AND HOW DO I REMOVE THE AUGER? I'VE REMOVED ALL BOLTS ON AUGER ENDS AND IT'S FREE BUT I CANNOT PULL AUGER OUT.