I too use heat to straighten the serious kinks out of a commercial rod. I use some oven mitts, a towel soaked with water, and a heat gun, a hot plate, or a propane torch for the work. Wet the rod in the are going to straighten, apply heat until you cannot touch the wood with bare fingers, bend the curve in the opposite direction plus a bit, hold it there for a time, and release it slowly. Once you have tried it, you'll see how easy it is.