Try running a short jumper wire from the red terminal on the engine block to the blue terminal. This will supply constant power to the distributor electric eye and the CD box electronics. (remember: Red to the CD box already supplies constant power to the capacitors only). If you now can get spark while cranking, replace the switch and/or the cable. If the switch is bad then you are good to go. If the switch is good, then the cable has an intermittent break in it (not likely) Simply run another wire from the ignition switch to the blue terminal on the engine.
