Issues with spark?? help??

I have a 1979 Honda cb750F I just got the crabs rebuilt, got them put back on, and all connected, the bike fired right up up sounded great, all i had to do was adjust the idle. Took it out for a spin road great, sounded great life was good......
Two days later i went to start it and nothing, the only way i could get it started was with the throttle pulled wide open, but as soon as i let it go it died, did not matter if it was full choke or no choke either. I checked to see if i flooded it some how took all the plugs out no gas, while i had them out tested compression 120 on all four cylinders. The i checked spark. 1 and 4 had great constant spark. 2&3 not so much. I got a spark on them when i hit the starter but nothing after that initial spark. any thoughts on were i should go from here, my next best guess is check the coils.

[TOOLS1]

Coil would be my first stop, but you also have ignition module, pickups, and a few connections in the circuit. You can download the factory service manual from our manual link at the top of the home page. It has detailed instructions for testing the ignition system.
TOOLS

i tested the coils one did not pass so i swapped them to see if this would give me a constant spark on 1&4 (i had previous said 2&3 that was my mistake 1&4 had always been the ones with the issue) i got the same result. I get an initial spark when i hit the starter and then nothing, mean while 2&3  are sparking away. This is were i run into a problem tried to get the cover off of the pulse generate to do the tests in the Manuel but the three screws that hold it on are not budging, and i don't want to strip them, i have tried penetrating oil and nothing doing, any advice on getting tat cover off so i can continue?

[TOOLS1]

Use an impact screwdriver. The kind you hit with a hammer. You can get them at Harbor Freight for less then $15.00
TOOLS

[Re-run]

Just make sure the bit fits tightly. A sloppy fit and you may as well have just used a crappy screwdriver on it.

Think i got it figured out bad pulse generator. on of them was cracked and when i tested its resistance it was 1 compared to the others 500 ohms. Going to pick a new one up tomorrow see if i can get her running. All i have to do then is read up on timing and learn how to do that