I didn't base my opinion of the belt being shot on it being 3 years old, but based on his description. Since there is no way to adjust the belt and he describes the belt as "real sloppy while running". I assume that the word "sloppy" in this instant is used to mean "loose". Since I am using the term loose and sloppy interchangeable, and the only thing that can cause a loose or sloppy belt is a belt that is too long, then it is time to change the belt. However, I might be mistaken, he might have a worn bearing that is allowing a pulley to lean to one side giving the belt the appearance of being sloppy when in actuality it is not the belt itself, but a defective bearing that is the real culprit. He doesn't mention noise as being a problem, so I will discount this bad bearing theory as not being correct and return to the belt being stretched beyond its useful life theory. I can only answer the question based on the information given. I can't and won't make any comment on how long a mower deck belt should last unless I were to have all the pertinent facts to make a proper mathematical time calculation. Such pertinent facts would be size of deck, hours of use, RPM of PTO, whether constant or intermittent, length of grass, density of grass, grass type, whether mowing in daytime or night time, etc. Then I would compare that to the the chart of useful belt life under normal lawn mower deck belt life simulation tables as established by the International Lawn Mower Racing Association published in 2003. /forums/images/graemlins/grin.gif