The first thing to do is to get a spark. As long as all the bits are present, WICO mags are very reliable and I've only ever come across one that didn't work after I'd cleaned the points. First off, rotate the engine and look at the points. You will (should!) see them opening and closing. Leave the operating cam in the open position.
Remove the moving and fixed points from the hole they live in, making sure you note where all the bits go - a digital camera is a great help for this sort of thing.
Get a sheet of at least 400 grit wet and dry, preferably finer and fix it to a piece of glass - wetting the back will do. Take the moving point and rub the working face to and fro along the abrasive surface until it is smooth and clean - don't try to take out every pit, if they have seen better days, there will be nothing left! Repeat this with the fixed point.
It is MOST IMPORTANT to maintain them as flat as you can and it would be no bad thing to practice with a nail head until you can get it right.
Refit the points and gap them at their open position with feeler gauges (if you've got them) to 18 thou. If not, the thickness of a postcard is about right.
Take the plug out and spin the engine on the flywheel. You should get a loud clacking sound as the magneto flick mechanism whips the magneto across its firing point and a nice fat spark should jump at least an 1/8" from the end of the bare wire to the body of the mag. Make sure it will also jump from the plug lead to the cylinder head as it would not be the first time that I've found the mag inadvertently insulated from the engine by a dimwittedly applied layer of paint!
We are all interested in what you're doing as you are at the most interesting time in a rebuild, getting it going, so don't leave us in suspense!
Regards,
Kim Siddorn,