To add a bit of color on the “take your time” comments: after perusing every thread on this forum I could find (lots) I settled on the wood block method. Have used it twice with near perfect result. See photo for my setup and note the two screws. Once snugged up I tightened those screws literally no more than a half turn twice a day. Repairing a 75 degree corner bend on a postwar 2034 it took almost a month total. I started bending to a 3.5 diameter arc first (which I read was the arc size Lionel used) and once I got there I went to a larger arc of 4 3/8 and just spot bent the corner only. The only heat involved was warming the whole shell on the hot Texas summer sun. I used hole saws chucked in a drill press to cut the arcs.