Hey I just recently bought an 09 jcw, there's a buzzing noise coming from the tachometer. It really comes to life over bumpy roads, if I just simply put my hand on top of it..it stops. I searched and couldn't really find a solution.

 

Mine does the same when it's cold out. I think something has worked itself loose, I may take it off and tighten up things in there...someday.

 

It's usually the red plastic light cover on the top of the tach that buzzes around because its not sitting tightly. A dab of clear silicone around the edges fixed it for me.

 

The tach is easy to remove and easy to disassemble. There are a couple of torx-head bolts that hold the tach down onto the steering column, if you pull the wheel all the way forward and tilt it all the way down you can get at them. If they're tight already, you can remove them to dismount the tach.

Then there are the three screws in the back of the gauge; remove those and you can separate the pieces out. You can get the silicone where you want it at that point, or maybe put some felt in to stop stuff from rubbing.

I posted a thread (with pics) showing the process a while back.