What is the preferred method of straightening a steel handlebar stem? I've got an old razorback gooseneck that is just a bit out of whack- it fits just fine in the frame, but the handlebars list a bit to the left, so just a little tweak will do the job. I don't want to put any more pull on it than I need to though. What do you guys suggest for small tweaks to straighten these things out, while making sure you don't pull too far?