You can eliminate all outside interference with the magneto (safety switch, ignition switch, etc.) by removing the wire from the post on the side of the magneto.
As noted above, you can remove the mag as a unit. Be gentle with the bakelite bits as they are easily cracked and VERY pricey if you need to replace them. Clean up the coil contacts, rotor and cap. Clean and dress the points, gapped as above. Test for spark at the coil with the caps removed. Ground the mag body against a bench vice, anvil, trailer hitch, etc. and hold the coil tang about 1/2" away from the steel bit you're grounding against. Spin the mag over (clockwise) and see what you've got. Should jump that gap easily.
