Hai,
a friend of mine had a torn hose under the carb, so we renewed the hose as the coolant.
Warming up the engine we noticed a leak.
It was just a matter of just turning the screw of the clamb.
We coudl only do that by loosing the bolt where the thermostat is attached on the frame.
Then we noticed no leak, but the temp gauge did not work.
I said lets, put back the thermostathouse at his place and my friend said: what if the thermostathouse is the ground of the gauge.
And yes, we just put the house on the frame and the gauge worked again.
There are issues with the temperature gauges, but i have not heared from this "solution". so that why I share it with you guys.
Make sure the themostathouse is clean and clean the spot where you mount it on the frame.
It could save you a lot of work