Any idea

I have an old Graco 3000 that runs intermittently, sometimes it starts and runs fine then the next time I go to use it, it won't start and has no spark. Any ideas what the problem may be? Thanks

Try changing the spark plug

My guess it is the magneto. It is what sends the spark to the spark plug kinda like a coil on older cars.

Definitely check the Mag and wire. I had one once that a screw worked loose and would cause the gap to change and it would run intimately.

Run the engine in a slightly dark place and look for sparking coming from hairline cracks in the plug wire and jumping to ground. Given the age of the machine it is quite possible the plug wire is going bad. The plug wire is usually part of the whole coil/magneto assembly, but a simple swap. just be sure to gap it properly (or at least close) when you put in the new one.

I bet it is definitely the coil,without a doubt,nothing else can produce those symptoms.(after you replace the plug..of course)

Be sure to disconnect the low oil sensor before trying to diagnose electrical. Take that variable out of the equation first.

If oil level is good and the sensor is ok then get a new coil.Without a doubt its going bad.