Stephen,
If your belt is an IH belt you may get a little more life out of it by flipping it over and putting it back on.
I've rarely thrown an IH belt on any of my tractors. But I have had all kinds of trouble with the belt getting flipped off of my parents 149. They are running a belt from the hardware store from the pto to the mower deck. I've also had trouble with the long hardware store belt on my sisters #2 tiller flying off while the IH belt for my tiller works perfectly.