I had to replace the belt on my New Idea hay rake. It is a round belt instead of a V- or hexagon belt. I cannot get it to stay on the rake. Every time I start to rake the belt flies off and I have to put it on, tighten it and start to rake again, it just come off in no time. The drive pulleys are somewhat rusted, does that have an effect? What can I do to fix this problem?