Thanks for that. I have already changed the condenser. The spark itself is very week indeed and runs the engine for about 2hours, then stops, restart and it goes on like that all day
Coil break down I think.
I usually take an ohm meter and measure resistance on the secondary coil to see if the coil is ok. I take the cover off the mag, remove the little spring that serves as the connection between the 2 coils and test each coil separately. All the coils that I have tested have a resistance of 3900-4400 ohms. If the resistance is infinite then there is a problem. If the resistance is a lot lower then there is a problem as well.
Not sure if this is a good method for checking a coil but its all I could think of. I have had only 1 coil that has been bad and it was bad because someone had tried to drill out the mounting hole and re-tap it. The accidently drilled into the coil.
The last time I had a weak spark on a Wico, it was because the armature wasnt sitting flat on the poles. The poles were un-even. I also made sure the points were breaking at the correct time.
When replacing the coils on an EK, the hardest part for me is removing the old coils. The coils are held in place on the cores by wood wedges driven in to hold them tight. Those wedges need to be removed before trying to remove the coils. Everything else is pretty straight forward, but the insulating pads between the coil and frame need to be replaced, as does the insulating strip between the frame pieces. Sometimes the spring that acts as the conductor between the two coils is corroded, but disposable lighters have several similar springs in them that have worked well for me.