Intek 20HP with no compression?

[Borolf]

I have a Briggs & Stratton Intek 20hp model 331777-0946-B2 engine in my Toro mower that just quit while mowing yesterday. It turns over fine, has spark and is getting fuel. I checked the flywheel key and all looks good. I'm getting no reading on my compression tester and can hold my thumb over the spark plug hole while cranking and feel absolutely no pressure. After removing the valve cover and spinning the engine the valves look like they are operating normally. I'm thinking maybe a bad head gasket? Anyone have other ideas or advice before I start to tear it down?
Thanks, Bob

 

[nfk]

The valves are moving but is the piston.
Put pencil in spark plug hole and turn engine over by hand
See if piston is moving.

 

[Borolf]

Pulled engine, pulled spark plug and looked in cylinder. Of course my luck...piston is not moving! I drained the oil, removed the dipstick tube, looked inside and there are large hunks of aluminum so I'm assuming failed connecting rod. I'll disassemble tomorrow to see if it's worth rebuilding or if it will be cheaper to buy a new one for $550.00 from Northern Tool.