PLT-1, I had the same issue When I rebuild my Engine I bought a new Dist Lock from Summit and recently when I checked my Ignition Timing it had moved (retarded) 10°. So of course Panic spread as I suspected the Pin was sheared. In fact the cheap Lock from Summit had bend and was not holding the Dist tightly. The Pin was Intact! Advise: Use the old OE Dist Lock its Rock solid.
@Husker btw even if the Rotor spins in can still be that the Pin sheared and its now out of timing. If I were you I would pull it and double check
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