My older recently acquired Sears Craftsman Drift Breaker snowblower runs rough and cannot reach high rpm's. This is a 12 horse engine, I think it has a tecumsah snow king engine. Purchased used, model number begines 536. not sure of the year. Starts right up and will idle fine. If I increase the throttle the engine never really produces any higher rpm, or at least not enough to "throw the snow" any distance. Could this be a altitude adjustment on the carb? I live at 8,000 feet above sea level in Colorado. Been looking online for detailed diagrams and have not found any that have been helpful. not very experienced with small engines and looking for some guidance. I'm thinking this blower is about 15 years old but not sure. It is a three stage model, has 14" auger blades, with the a chain drive small drift buster auger on the top, above the main auger.

What is the part called that the snow is discharged from? Where can I get this part? I bought a used snowblower from a couple who PCSed(moved to another base). Where can i find this part! THANKS!