Check the upper distributor shaft bushing for looseness by trying to move the rotor from side to side. It sounds like you might have developed enough of a wobble to let the dwell change from one place to another as the distributor turns, resulting in an intermittent miss. If the wobble was bad enough it could have let the rotor make contact with the cap and knock it out of position.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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