"80 280 CE starts every other day....
 

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.

Probably the control unit on that one, but of course the first step is to evaluate the impulse signal from the distributor, basically an induced sine wave.

I take it I need to take it to a shop when running so they can make a sine wave measurement (control units cost about $250)?