Small Engines (Lawn Mowers, etc.): Yardman 13AJ771G713 42 deck, wal marts, ace hardware

Question
I bought a used 2005 yardman.  the drive belt falls off either when the PTO is engaged, or put in forward.  I took the deck off and noticed the spring extensions missing. Replaced, but belt still falls off.  The guy I bought the tractor from gave me a larger spring, about 1" thick x 5 inches long.  I don't see where it goes in the Parts Manual, only the replaced spring extensions.  The  deck belt is very loose and it still falls off. Is there an adjustment I'm missing?  Or is there another spring I can attach to get the belt to stop being so tempermental?

Answer
Claire,

   One of 2 things is going on.
1. the belt is the incorrect size in which replacing the belt will stop the slipping off.
2. The Belt Guards are missing MTD Products are notorious for the bel guards and when you change the belt you always need to remove the guards Another thing to try is if you push down on the PTO and watch how it tensions the belt (dont start the tractor while doing this please) you will see  if the belt becomes fully tensioned or not If it does not and its still loose then your belt size is wrong any Ace Hardware dealer Carries MTD belts Even Some Wal Marts.
Give them your tractor model # and Deck Size and they will fix you right up
Also the belt tensioner is another pulley wheel that presses against the belt that engages the drive if it is not pressing against it when you let off the clutch/brake then it is the one that needs the new spring attached to it