Outdoor Power Equipment and Small Engines - Ryobi 780R

I am having trouble with my Ryobi 780R..and hoping someone can help. It was running this year, and then just died and I have not been able to get it going again.
I have checked and replaced the spark plug..my tester shows I am getting good spark. I have replace the fuel lines. I have rebuilt the carb and the plug is wet, so it is getting gas.
Compression is good. The switch seems to be working, the plug sparks when it is on and does not spark when turned off. I have removed the muffler..it is clear and the ports are clear as well.

The machines does not even attempt to run....You pull and pull but nothing. I have even used that sure start spray from the local hardware store...but nothing..it does not attempt to start....
Does anyone have any ideas

Thanks

A sheared off timing key in the flywheel or a massive air leak could cause a problem like you describe. I would check the flywheel key first and if that checks out ok then I would look for loose mounting screws around the crankcase cover, cylinder and carburetor and finally the crankshaft seal.\

Good Luck...

I'll second the checking of loose mounting screws on the cylinder.

I'll third that. Had that happen to me before.