Campag Brake/Lever Rattle

About 6 months ago, after I installed a new front deralieur cable, my left shifter (Campag Daytona) developed a rattle. When I shifty to the big chain ring (ie. tighten the cable) there is no rattle. In the small ring, it's like a pair of maraccas! My initial reaction was to try and tighten the cable but no cigar!

There is no visible vibration, that is, the shifter and brake lever aren't knocking together so the rattle must be coming from inside the actual mechanism itself.

As I didn't change the cable housing when I installed the new cable, I thought that might have been the problem. So I installed a new cable and housing but still no luck.

The funny thing is if I take the cable off altogether, no rattle when I bounce it on the ground.

Any help greatly appreciated...