That diagram is somewhat confusing. The brown wire(J3 16) should start at the ignition switch and should end at the output end of the ballast.(bypassing the ballast during start) The brown wire should connect directly to the blue wire at the ballast. The blue wire then runs to the coil.
That is how I've always seen them. The brown wire changes to blue at the ballast and then runs to the coil. Maybe they changed it in 75? Can the OP post a picture of the ballast and all the wires that are attached to it?
