Cylinder 1

Pop the valve cover off, you'll see pretty quick if that was the case. If I recall the rocker arms have a tendency to fall off, the lifters have a poor design and don't get enough oil, lets too much lash into the drive train, causing rockers to fall off and valves to drop. If adjoining cylinders have good compression I'll bet this is what happened.

Thanks ill check it out.

It could also have a broken valve spring causing the valve to stay partially open.