Might also be worth having a look at the metal pin/tab on the side of the glass.  Depending on the make of DMD, they can crack and can be soldered back together pretty easily. 

That was my first thought, could also be a dirty connection, try reseating both ends of the wiring loom going to the DMD and the board.
Could also be a cracked solder join on one of those header pins giving an intermittent connection