It took 1/4
To do the job properly I should remove the existing weight first, and start again.
However, I am replacing the original dodecagonal snowflake after twenty years of walloping, with a nice straight flake.
Can't wait to check the rear......

So I'll balance the new front wheel (find the heavy spot) with a tube on it before putting the tyre on and balancing.
I might even get an approving nod from Duane and Vanzen! (a nod from Vanzen except for the tube thingy.)