I have seen a vent frame twisted around 3 times from a very ham-handed, yet dedicated person. Looked like fancy twisted wrought iron work. He finally broke the spot welded bracket off on the final turn. (Not me, By the way.)
The hard part with loosening really rust up ones is finding a way to hold the end of the frame while simultaneously turning the bolt.
I always replace the bolt with a stainless steel one.
Carl
