You might also consider using some stainless steel threaded inserts. That way, you drill out the crack, alleviating the stress. You also use a machine screw thread like an M6 or 10-32 to hold down the screen mounts. I used them to repair stripped wood screw holes in the ash behind my dashboard.
Geoff, the screws are close to the edge of the dash board, that's why it cracked. Also, the board is angled, so installing threaded inserts won't work. I'll post some pictures in the morning.
