[rotorwrench]

Hall effect magnetic pick up assemblies are pretty reliable. I've only had one go bad on a Chadwick Strobex trigger set up that I use to track main rotor blades in my whole career. I think it went bad after it got smacked real hard or one of my mechanics dropped it from the top of the helicopter to the concrete pad below. A lot of the aftermarket ignition boxes are less reliable than the average chebby HEI.