Check the distributor very closely, mark it and remove it after removing the cap and rotor. Check that the three wires from the hall sensor to the plug are in good shape and that the plastic plug in firm in the distributor plate. If not the plastic housing can be gotten from a dealer for a few bucks and the contacts carefully removed from the old one and installed in the new one. This plug must be secure in the same way that the points wire had to be there in an old style distributor.