Your coil looks fine - the rough texture shouldn't hurt anything. Now if you see black tar leaking out of the coil then your coil is toast.
The 1/4 turn with no movement is called the "impulse" and is designed to retard the spark to TDC so there is no kickback while cranking and to throw a bigger spark at slow speeds such as while hand cranking the engine. This is totally normal and those seldom give trouble.
The black knob is the kill switch that grounds out the spark. Usually they are mounted on a spring that you simply push in until the engine stops. That one may be designed for a wire to screw on to allow for a remote kill switch such as on handlebars. ??
Put some oil on the felt that rides on the shaft inside the mag. That is the only lubrication for the black plastic arm that actuates the points. If there is no lube on the shaft it will wear the actuating arm and the point gap will change/lose adjustment.
That little black knob is spring loaded.
I cleaned up, and set the point gap to .015". Burnished all the connectors. cleaned up the
plug lead socket in the end cap of the mag. Clipped off a bit of the lead, and reinstalled
the contact onto the lead. Got a known good spark plug. No spark.
I'm not getting as loud of a snap, as on the other 2, that have the Wico Mags. (or as the FM Mag
on the Wisconsin, on my Gibson)
So, where do I go from here? Replace the condenser?
What tests can I do to find the issue?