Hi All,
Dave, I made up a "spanner" from a length of steel pipe more or less the diamater of the nut.
Cut away the end of the tube to leave 2 pieces that will fit into the sprocket nut, I welded a big nut to the other end
and do up the nut with a rattle gun!!!
The oil will leak out along the splines when the nut is loose!!
A thin O ring between the sprocket and bearing helps seal the spline
I just use thread lock on the nut! works for me
HTH
John O R