Lucas electrical systems- - - - -that's why the Brits drink warm beer - - - -they've got Lucas refrigerators!
Check out the connection where the point spring attaches to the distributor breaker plate. As I remember it, it's very easy to get a ground there which acts like the points are closed all the time. My MGA had a similar problem. It's been about 30 years since I've worked on that system, so my memory is a little fuzzy as to exactly how the insulators assemble. If the wiring harness is grounded there, the trigger signal never gets to the Pertronix amplifier. If it's been that way for very long, you might have fried the amplifier. Yes, I know the Pertronix eliminates the points, but the connection could still be wrong.
Jerry
