Don't use silicone spray. Don't use cooking spray.
Use Ski wax, skateboarding wax, hard paraffin, or turtle wax on the entire interior of the blower, including the blades, chute, and any surfaces that receive the snow spray.
Tab has some good suggestions too, make sure the engine is running right. I'd personally take it out on a warm day and run it just to blow away all that carbon and crud in the carb. Get it good and hot. and make the belts are correct, then let it cool down, and check the belts again.
I thought most snow blowers were chain drive... I guess not.