What's the Best Lube for a Speedo Head?

[colnago]

All,

I've been chasing down problems with my speedo lately (cluster from an F600). I'll be removing/checking/lubing the cable, and also lubing the speedo head itself. The word on the internet is that lithium grease is good for the cable, but opinions vary on the best lube for the head (graphite, sewing-machine oil, nothing, etc). Has anyone here done any R&R to one of our truck clusters?

Thanks,

Joseph