New weird hum/whine right behind gauge cluster now?!

[DieselPop]

So I just managed to adjust and fix my alt-belt tension and thus recharging problem, which then started a little belt squeeling new problem which seems to have died down now.

It's hard to imagine that this is related, but right after fixing the above problem, I am now getting a weird hum/whine sound from what seems to be right behind the gauge cluster. It's def. related to speed of travel also. Another factor is that it only seems to crop up in the morning (cold, in 30's) while going to work, but then does not exist on the way home (high 40's low 50's?). I am thinking that it is somehow the speedo cable, and it's somehow sensitive to cold? Theo only other thing I can think of is perhaps the slow-idle knob and cable connection?

Any ideas out there? Common proboem perhaps? I've pulled gauge clusters, so I'm hoping it might just be something easy I can oil...