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Wrong coil should only be too strong or too weak. Not intermittent.

I think your problem may be the cabinet buttons. They are high-current tungsten contacts that can get pitted. The end-of-stroke switches as well.

ES flips1 (resized).png

Try filing them with a contact file. Brush away or vacuum the particles.

If it still has problems, unsolder one of the capacitor legs. It may have caps on the coil EOS and the flipper cabinet switches.

Let us know how it turns out.

Your description also can be a symptom of the crank being too far up the flipper bat shaft and binding on the bushing. Oh, a broken bushing could also cause issues.