I have a Noma 29" 10HP snowthrower with a Briggs&Stratton engine. There is a plate that says Murray on it. The auger works great and throws the snow very well. The engine will start on the first or second pull. The problem is that it won't move forward or backward anymore unless I'm pushing or pulling it. It used to move when you engaged the left lever. It is at least 6 years old and I don't have any sort of manual for it. I opened up the skid plate and the friction plate has a few small scores on it, but it's not that bad. There is a loose snap ring around the bar with the friction wheel on it (the one that the wheels are attached to) - I can't see where it came from or what use it might have. Does anyone have any ideas about how I can get this thing moving? Thanks.