The magnetic pickups are pretty reliable, they will usualy work or not work, unless there is a wire that s almost broken in half except for one or two strands It wouldn't suprise me that your problem is in the ignition wiring or the ignition switch, not the mag. pickup in the distributor You can always check the pickup with a Ohm meter, use the lowest scale you can select and test between the black and the other color(there has been more than one positive color of wire in the pickups over the years, the black is the negative side of the pick up)Disconnect the lead to it and use the Ohm meter leads hook one side to each of the pickup connectors , wiggle the pickup wires around while maintaning a good connection to the test leads, if it goes open, infinite Ohm reading, instead of 200 to 500 ohms thats your problem If not, look elsewhere