The Boyer failure I had was proven conclusively by swapping in another box, with no other changes.
When the Rita was introduced on the 1979 Triumph T140 it was plagued with failure. We that's what we thought at first. Replace the box under warranty and the bike came back to life. "Bad" boxes were returned to Lucas, tested and then returned to the dealer. The box was good. It turned out that by swapping out the box it restablished the connections to the trigger plate in the timing cover. Box good, connections bad.
The original Rita had a 5 wire connector located in the area where it was exposed to water spray from the rear tire. The trigger connections would corrode. The solution happened when they moved the trigger plate connection up under the fuel tank.
"The Boyer failure I had was proven conclusively by swapping in another box, with no other changes." You did make a change! By disconnecting the old box, wih possible corroded connections, and connected up a new one, it is possible that the new conections cured the problem.