gauge cluster help

[P.J.]

My 70 chevelle gauge cluster,water temp guage did not work so
I changed it. the car has a new wiring harness from factory fit, also enjine harness is new. After changing the new GM NOS gauge it still does not work
I made sure that the new gauge was installed correctly
and there is a new printed circuit installed.
I checked the heat plug on the motor its seems to be ok
and still the gauge does not work
any Ideas on how to fix the problem. Do those heat switches
on the motor ever not work??
PJ