Fluctuating neg. to ground on ignition coil

Well, I replaced cap and rotor a couple of weeks ago, so they should be OK.

Pulling the distributor shaft sideways revealed NO play at all as far as I could feel with my bare fingers.

Finding a workshop with a Sun machine in this remote part of the globe will not happen, I have yet to find a workshop that has an oscilloscope, chances are small to find one...

View attachment 1715546033 View attachment 1715546034 View attachment 1715546035 .
Very interesting I thought for sure you would find some play in the shaft.
A lot of corrosion inside the distributor, I hope the mechanical advance is operating properly.
This miss you have are you certain it is only at idle rpm?