Murray riding mower 38 inch.

Murray riding mower 13 hp Tecumseh Enduro. Mower starts and blade engages. Currently will not move. I have too many projects. Possibly needs fluid, tighter belt, I’m not sure. there may be a trick to engaging the rear end that I don’t know about. I haven’t been able to find too much information on it. Murray New carburetor. Front tires need to be put back on bead but tires look to be in OK shape. Mower, mowers, lawnmower, lawnmowers garden tractor