I’ve had to move the distributor slightly one way or another to find the sweet spot to catch and run. It has to be running to use the timing light. It can really be a pain sometimes, I know I spent a couple days trying to get my one to run and I still don’t know what changed because all I did was hook up jumper cables when the battery ran down from trying to start and I still had a little time that day to mess with it. Not saying that will fix yours because it shouldn’t have done anything. I tore the motor partially apart, replaced the battery wires, cleaned grounds, re-set to TDC and re-set the distributor probably 20 times. It can certainly be frustrating at times.