Yeah, the hanger may be bent as well.

For straightening all you need is an exposed beam, some 2x4's and a small bottle jack and a few hand tools. It involves some creative work to make a press using the beam for your house from above, the floor below (probably concrete assuming you're doing this in the basement) and some 2x4's cut with U grooves to support the tubing and the bottle jack to provide the pressure. A pair of nailed together doubled 2x4's will provide the extendion to the beam. Use two 2x4's on edge with U's cut into them and one under the pad of the small bottle jack. Put the lower two supports about 2 inches to either side of the center of the bend or at the ends of the arc if it's a longer gentle bend and put a third short section on edge with a U in it in the middle and then place the bottle jack on top and the doubled 2x4's on top of that and jack until the extender touches the support beam and then look carefully at the leg or frame tube as you apply pressure. Go a hair beyond straight and release. Repeat as and with as much force as needed. Reposition the cauls if needed based on how it's bending. Some trial and error will be needed but don't go past and then correct. Sneak up on being truly straight and move the cauls around if it seems to need this by closing the spacing up or widening it out or shifting off center or whatever is needed to get the job done.

No need for anything more unless you're planning on making a habit of this....