1994 Oldsmobile Bravada Speedometer

Here's my problem; Once in awhile my speedometer and/or odometer will fade out and I cannot see either of them. Also, if I tap or bang my dash, the gauges will come back, but will eventually fade away....again. My instrument panel is all digital, like a tetris game kind of. My question is, would it be a loose connection or...? Thank's for your time.