Instrument Cluster Problems

[TM]

Can any listers please tell me where I should look to see why
my water temp gauge has failed?

Patient is a '91 200q, everything worked fine until I decided
to mess with it and replace some instrument cluster bulbs. Now
the water temp gauge doesn't work and everything else still does.

Replacing the multi-function temp switch (MFTS) has not changed
anything, although I don't feel bad replacing it as it had a
date code of 11/90.

Taka