154 with 3260 mower

I have painstakingly rebuilt a 3260 mower for my 154 lowboy, but amhaving zero luck with the belt that connects the 3 blades, I had a lengthy conversation on the Phone with Hamilton Bob (great guy) and he gave me some great advice but still it eats that belt the belt is not rubbing I have sandblasted the pulleys and put them in a lathe and polished them but still after about a half hour of run time the belt looks as though its all cracked and broken, anyone have any more suggestions, I am at whitts end with this thing any and all advice will be greatly appreciated

What brand belt are you using? I've had similar experience with Gates belts. My neighbor has a Yanmar tractor with a Woods belly mower which uses a long belt that twist & turns all over the place. When it needed a new belt I measured it and got a Gates replacement. Within an hour, the belt had cracks all over and broke. I thought it was a freak incident and tried it again with the same result. We then got a Woods belt, from the JD dealer and the problem was solved. Some belts just can't withstand all the back bending and twisting that many of these mowers put them through. I know the proper belt, from IH, is considerably more expensive, but I feel it,s the safest route to go. I'm sure there are other belts that will work fine but who can afford all the experimentation to find out?