hah! i've wondered the same thing myself. There are two scenarios that I know of that are causing this (my car had/has this problem too).
Something to consider: the problem might not be in the cluster circuitry at all--there might be a short in the lead from the cluster to the ECU.
obviously bridging the contacts on the back of the cluster would be the easier possible fix, but that might also kill the signal going to your speedo (electrons take the path of least resistance), which would make your speedo useless to you.
i guess there's no harm in trying that (except the CEL, which would comes on anyway). i'm curious to know what you'd find.
1997 Sentra GXE, GA16DE, M/T