Try our re-instated info resource - "Aladdin's Cave" (Main menu)- sorry it's taken so long to fix
Good No Ted, if you fit allen keyed bolts you tend to either shear them off or most often you strip the thread clean out of the backplate, they can exert far too much pressure for such a small screw. Use crosshead screws, they tend to slip and round before you can strip the thread out.