tony1z,
Ariens uses a "Friction wheel" to drive the machine, here is how it works, so you can explore the reasons why it is not.
The engine is connected to a belt that turns a round aluminum disc called a Drive Plate so long as the engine is running. When you squeeze the handle to engage the drive that Drive Plate moves enough to contact the rubber face of the Friction Wheel, which turns at right angle to the face of the drive plate, when they make contact the machine moves because that 'Friction Wheel' is connected directly to the tracks or wheels. The 'speeds' are controlled by a cable that can slide the friction wheel sideways across the face of the friction disc. When the rubber face or 'tire' of the friction disc is at the edge of the disc the machine has more speed, less power, when the friction wheel tire rides at the position closest to the center of the Drive Plate the machine is in low speed, max power. The reverse positions simply slide the friction wheel to the other side of the rotating Drive Plate which makes the friction wheel turn in the opposite direction. So If the machine is not moving, here are your possibilities for that:
1- the belt driving the Drive Plate is not gripping the pulley or drive plate properly because it is a) Worn b) Stretched and needs tightening c) the pully is polished and needs something to help the belt grip it
2- The rubber Tire that is the face of the 'Friction Wheel' can need replacement because a) it is worn smooth b) cracked and broken c) has a flat spot
3-The Drive Plate itself can be worn smooth to a point where it no longer grips the rubber friction wheel and this usually occurs under a heavy work load. (some Mfgrs require replacing the drive plate, others like MTD simply have you roughen the face of it with sandpaper).
So Good Luck !
I'd start with the belt, its the easiest fix to try.
After that you need to look under the machine at the friction wheel gizmo I just explained.
