If you have a long pry bar to can wedge it up under the body somewhere and have someone push against the head of the wrench directly over the plug. A small piece of wood (1 X 4) between the pry bar and the wrench head makes it easier. Sometimes they come right off but when they don't you have to be careful not to make things worse. I've never messed one up using the pry bar method as long as the the wrench square fit nice and snug. The few I did round out (before I learned) I saved by grinding a larger square down until it basically wedged itself into the rounded hole (using a hammer), then lots of pressure and BINGO!!! Treblig