On Fri, 20 May 2005 17:57:32 GMT, shane
wrote:

Someone has tried to remove it before slightly rounding the nut so that
now a socket will not fit.

The best tool to remove it is a socket. Go and buy one - a six-sided
"flank drive" socket, preferably from Snap-on. These put their force
into the middle of the sides, not on the corners, so they're less
affected by rounded corners and they're also less likely to round the
corners further.