I've never had a problem straightening circular needles, even Boye's.
I bring a pot of water to a full rolling boil. When it's ready, I turn on the cold water faucet. While holding the needle tips, I dunk the cable into the water for a few seconds, making sure it gets good and hot. Then I hold the tips apart to straighten the cable and run it under the cold water to cool it rapidly while holding it straight. Every cable as come out straight or nearly straight for me. HTH!