Can't say I've noticed them before, HP, even though I've changed quite few MCP's and VOR control panels, but now that I think about it, I'll hazard a guess and say that they are equipment cooling flow sensing lines. If you look over your shoulder to the 1st Obs panel, you'll see an equipment cooling test panel which consists of a thin plastic pushbutton below a row of clear, vertical tubes. You push the button and watch little white balls rise up into view inside these tubes indicating that the equipment cooling air flow is OK. No doubt, one or two of these "test tubes" will be marked VOR or MCP?
Cheers.
Ia... er... Q.