I used to have another old bow which had a similar tendency to twist. You could just detect the twist when the bow was unstrung, but once strung it looked straight. However, when I pulled it I could see the limb twist a little, the string never jumped but it always worried me. I tried the hand twist and heating with a hair dryer; but the limb seemed to always return to its former state. I resorted to putting the limb in "traction"...so to speak. I used a 3/4" dia. stick about a foot longer than the bow. I secured the stick to the bow on the opposite side as the direction of the twist; making sure to stabilize the riser and good limb. Next I twisted the tip of the offending limb to the opposite side of the stick and secured it in place. next step I heated the entire length of the offending limb. I heated the limb evenly until it was very warm, but not uncomfortable to hold,( I felt this would keep the old glue from getting too hot and releasing). After heating I left the bow in traction over night. After carefully releasing the bow from traction I strung it and gently pulled the bow about 5 times watching the limb for twist. I stored the bow strung for a couple days, then unstrung it. I repeated this process until the twist disappeared,(4 or 5 times).
Might have been unconventional but it worked. The bow shot great with out any other twisting the rest of the time I owned it.