I've got a Murray Snow Blower - 2 years old. I believe it's an 8 or 10 HP. It doesn't move forward in low gear. I have to push it and then the wheels move a little bit. The higher gears seem to work fine. The snowblower part of this works fine as well.
Jungman7

Have a look at the friction wheel see what happen when it is in 1st gear. If the rubber is not touching then that is your problem. If it is track driven it is common.

Murrays use a fan belt as opposed to a chain. Sounds like your belt may be slipping. There is a spring loaded pulley along the belt which is supposed to apply enough force to create friction. Check the pulley and see if tightening the adjustment bolt doesn't give you better traction.

Ball, sounds like you know about these snow blowers, imagine that, you actually have the darned things in your area. I am glad we do not.