temperature gauge question

[Dixon <biwltud@bellsouth.net>]

What are possible causes for intermittent operation of the temperature
gauge on an '89 100?  Following the Bentley procedure, I have checked
the resistance of both sensors on the upper cooling hose ( ~3.3k ohms at
50 deg F and ~230-250 ohms when hot) and the voltage on the connecting
harness (4.95V on one terminal and 4.75V on the other).
3.3k ohms is above the spec. in the manual, but the resistance does seem
to change properly versus temperature.  Is there something in the gauge
unit itself (I don't look forward to the idea of dash disassembly) that
typically fails?  It appears aggravated at cold temperature.  Thanks for
reading.

Adam Dixon
'89 100  130k
biwltud@bellsouth.net