Yep, looks like the cap is missing the carbon button. If it's missing then it's time to replace the cap. I would replace the rotor too as it may have been spark jumping

The terminals inside the cap look fine. That's normal condition after it runs a while

The rust particles inside the cap (and on the rotor) look suspicious, but can be cleaned off with soap & water


with that type of distributor cap (screw down) it can be put on crooked, so visually check the fit before tightening the screws

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  rotor button.jpg (17.42 KB)