coolant temp gauge not working - '91 accord
 

for a few time now, the coolant temperature gauge on my accord 2.0 '1991 has
not been working. i tried changing the sender unit, checked fuses - nothing.
then i removed the panel in dashboard and found out that the pointer had
came off the gauge spindle. i pressed the needle back and now, as i start
the engine cold, the needle moves right up to red area. but the engine is
still cold.
i checked the shop manual and it said, if i connected the wire to the ground
and then turned ignition on, the pointer should move right toward HOT mark.
i tried that and so it does. then the manual said - check the resistance on
the sender and it was also ok. but no-one says anything about, if both -
sender and gauge are ok by the shop manual, why the pointer moves also up
when engine cold and wire connected to the sender.
i firmly believe that i pressed the pointer back in the right position,
because coolant temp pointer has no "stopper" in the COLD position as the
poiners have in tacho and speedometer. it just moves to the top as if the
wire was connected to the ground, not to the sender. has anyone experienced
spomething like that? all other gauges and lights are working just fine.