I have had a couple recurves straightened at a local archery shop by a older gentleman, that owned the shop, who was a trad archer since he was a kid. He said he would use heat and steam in a wooden box he made that fit just the tips. He said that you should only twist it back a little bit at a time time until it was straight again. But I dont believe he did it all once. He would do it then let it set and cool down then do it again and would continue the process until straight.