When the rotor arm rotates, does it describe a true circle, or an oval?
The spring clips that hold the cap down are not the most robust (as compared to the original 25D dizzy clips and Lucas cap) and the cap can be easily displaced which means when it is, the cap itself is off-centered just a bit and the rotor carves the contacts (proof is the 2 that are machined by the rotor; the opposite ones show signs of arcing from the increased clearance between the rotor and the cap.)
Is the distributor itself rotating properly, or is the cam that triggers the spark eccentric?
The issue lies within the design/material used for the spring clamps. It's an electronic dizzy, so there is no cam, only moving part is the rotor (and advance weights). This is the second time this has happened, so...thinking of ways of modifying/adjusting the clips to make them hold the cap on more securely.