I need to change the belt on my mower can`t get belt off pass pulley on crank

Deck belt must be off first. Put the tractor in neutral, have someone depress the clutch/brake and reach under the deck to pull back on the spring tensioner. Most pulleys have a "keeper pin" or two and the belt must be rolled between the pulley and the pin. The keeper pinis designed to keep the belt from jumping off the pulley, sometimes they work too good. http://www.ehow.co.uk/how_6077079_change-belt-craftsman-garden-tractor.html