I've had trouble removing the brake lines at the caliper and especially at those flexible lines. I know they're on snug. But I have a tendency to strip those line heads even with an 11m line tool. Even though the wrench seems to fit tight, my first attempt to remove usually ends up stripping it. Then a get out a small vice grip and I may get it, but now the head is gone. What am I doing wrong? Is there a better tool?

Thanks, Bill