Re: Mast bend?
You can't always be sure what is causing the problem by eyeballing it, so you need to diagnose it first. It could be that the top of the mast is falling off to one side, or it could be that the middle of the mast is bowed one way or the other. I would start by using a halyard to see if the distance from the top of the mast to the chainplates on both sides is the same. If they aren't, then your remedy is correct. Count the number of turns that you loosen the shroud on one side, and tighten the shroud on the other side by the same number of turns, until the mast is straight.
If the chainplates are the same distance, then that means the upper part of the mast is centered, but the center section of the mast is out of line, and you need to adjust the lowers, by equal numbers of turns, to bring the center section into line.