Have you thought more about swapping the cluster to see if one of the small resistors etc has gone bad?

I've got a known good cluster on the way.

I got the new cluster on Thursday and swapped the main board and right hand board into my cluster (in an attempt to keep my odo the same). Appearantly, the mileage is not kept in the DIC like I thought. But they all seem to work so far.

Not even a twitch in the wrong direction with the new cluster. I think all is well.