There was no idler pully on either tractor. The water pump pully should be made in two pieces. The v belt was tensioned by adjusting the width of the water pump pully V. It adjusted by loosening the screws and rotating the pully halves, changing the width of the V. Most of the ones I have run across are rusted solid and can't be adjusted anymore. I have found a couple that were welded and can't be adjusted. I managed to free up most of mine but it was a long process.