Quote Originally Posted by Rambozo View Post
Hard to see what's what in your picture. It sorta looks like the center longitudinal tubes are too long for a straight line. ...
I'd have to agree here. Did the other ends separate from the top (according to the picture)? Did you put a good tack welds on all the pieces before you did your final welding?

Another quick and dirty option would be to take a chain and hook to your two outside corners (bottom of pic) and put a jack with a sturdy piece of box tubing or a 4x4 against the center of the bow (that will spread the load out about 1/3 of the total length of the bowed piece) and try to press it back into position. You will have to over bend it a touch then relax it. Check for straight, rinse and repeat as needed. I've found that once you put the slight over bend in it, to either give it a little heat or a firm smack with a hammer to "shock" it and keep it in position. Bear in mind that this is a trick I learned in the field when equipment and options are limited, and you do what you can with what you have available.