No Hours on VDO Tachometers

[Newbie7749]

I have a 2006 Coronet. Both Tachometers show RPMs fine, both backlights work but neither of them shows the hours. If it were just one I would think it was a loose/corroded connection but that seems unlikely since its both. Every once in a while underway I can see some garbled text where the hours should be. It sort of goes in an out. 

Is it better to just replace them? And if I replace them can I program them to start at the current hour read?

Any help is appreciated.