My guess is also down on compression. The spark is hard to see, so i'm saying its there kicking or pushing. could be weak, which would be a bad connection or loose or bad ground. Nothing should be happening to ignition differently when kicking or pushing, other than it turns over more. My 250 would not be easy to push start cold, on flat ground, so I'm agreeing that its compression. Everyone says they rebuild them, but they often are calling rings and a gasket a rebuild. Better look in there and see whats going on with piston and cylinder plating. you can pull exhaust pipe and look in that side easy to do a quick inspection of rings, piston and cylinder. Thats just one side, but you can usually tell alot from looking there. Once the plating is chewed away, compression goes away fast.