compression issues

[jmasters]

I have a friends 1992 960 w/no compression on cyl. no. one. He said it made a noise like the muffler dragging and started shaking & missing. Looking into plug hole I see no debris& plug tip isnt battered up.Pulled upper cover & cams but all valve stems seem to be still at right level as if valve heads are still intact. Any suggestions before I pull head?

 

[jmasters]

Well I pulled the head & found a burned exhaust valve. Every thing else looks good so I replaced the valve & am in the process of putting it back together . Wish me luck! Lol.