1971 Duster water temp gauge inoperative

I have a 1971 Duster I purchased 2 month ago. The water temp gauge did not work, I have done the following:

• Replaced the sensor (twice)
• Replaced the Circuit board
• Replaced the gauge
• Replaced the voltage reducer (twice)
• Checked continuity From engine to Gauge
• Grounded the sensor not install, heated with lighter gauge worked
• Installed ground wire from bolt on intake to master cylinder
• Wrapped the sensor (installed) with wire to negative post on battery
• Water comes out or the hole the sensor replaced

Water temp gage still doesn’t Work.

Any ideas