You could also try swapping with another coil to see if the problem moves with it.

I'm in agreement though, that behavior is typical of a broken hold winding on the coil. You could also try comparing resistance readings between the problem coil and the good ones. You may have to open the eos switch to get accurate readings (or remove the wiring from the coil).

You might even be able to find the very-thin coil wire broken off from a solder lug on the coil, though it's not always where they break. If you do see it and it's loose, you may be able to solder it back onto the lug.