My '80 280 CE w/ M110 ran great the night I bought it and I stopped and started it many times. The next day it didn't. the next day I un-hooked and re-inserted the green cable coming out of ignition control unit and it started right up. The next day it would not start again after repeat w/ green cable. All ignition components look great but I am not getting any spark. Any ideas....? This cycle has repeated for 10 days.