Looks like the UP605/8461 was made for Aircap by MTD for just 1 year (1989)... the equivalent MTD model number was: 319-550-002
Here are some links to sources for available parts along with obsolete replacement/aftermarket recommendations:
MTD UP605 8461 319 550 002 Snow Champ Self Propelled Snow Thrower 1989...
MTD 319 550 002 UP605 8461 1989 Parts Parts Diagrams
The parts that go bad the most often are the wear skids on the outside of the auger housing, and the shave plate along the bottom edge of the auger housing.
Carburetors tend to gel up from the 15% ethanol the farm lobby got congress to put in all our gasoline, but that's not really 'going bad' - often you can actually clean the 'varnish' out of the orifices and passages with aerosol carb cleaner... shops would have a heated (about 105F) ultrasonic parts cleaner, but it's usually cheaper for DIY'ers to buy a new carb.