The pick up coil can't cause the failure so look to the grounds on the coils.... Make sure the mating surface to the frame is clean of paint and rust. Our bikes have metal clips that the coil retaining screws go into so make sure they are well grounded to the frame. Throw on a bit of dielectric grease and clean the threads of the screws to secure the ground. I'm pretty much thinking that might be your problems root.
