My Vincati has a electronic Smiths tachometer fitted and a B-TH modern magneto, I fitted a moto-gadget pulse sensor to the high tension lead and it’s been working well now for over 10 years, surprisingly even with non suppressive plug caps. Recently I decided to fit a rebuilt Lucas KVF magneto with a new ATD and I clipped on the pulse sensor the tachometer fluctuates but mainly stays wound around the dial. I immediately fitted suppressor plug caps, then rechecked the setup of the tachometer, I made sure the leads are isolated from each other and removed the kill button wire, still the same problem, I’m bewildered what’s wrong anyone got a idea how to fix it please?