OSD Menu visible, but not video fromPC

Hey...I've got a problem with a Samsung SyncMaster 955DF monitor. I believe it to have been damaged by jarring of the unit or jerking of the cable.

Anyway, the OSD menus (and "no signal present" message) are visible on the screen at the appropriate times. However, video output from any PC's video card (I have tried multiple PCs) will not be displayed on the screen. The LED changes from amber to green when a signal is present, the monitor "clicks" to change display modes, but nothing shows up except a blank screen (or, of course, the OSD menus if activated).

The video cable itself seems fine. I removed it and checked it for continuity between the D-SUB connector and the internal connections, and also for shorts between pins that should not be there. I suppose it is possible that I missed something in this, but not likely.

Any ideas of components or subcircuits (i.e., the video amplifier?) where damage to them would cause the above-mentioned problems (and could possible have been damaged by force?).

Thanks in advance,
Dustin