My Mighty White 95 Z28

Hey everyone, I notice that my trip meter does not work right. When I press the button to reset it, it works all the way up till 9 miles and it won't turn anymore it stops, but if I hit a bump or tap the dash board it will turn. What could it be? Would I have to take my gauage apart and replace the trip meter? Is it easy to? Any suggestions and advice would be greatly apprecaited. Thanks.