Some good info provided here. I also could use some help as I have a similar issue. I have a HQ & the temp indicator hardly moves also. I have tested the indicator with a decade box & is fine, it has a new thermostat fitted. So now I'm thinking the sender, after all the previous info provided by you all. Any chance of anyone knowing the P/n of the 74 HQ GTS temp sender. That way I can check if mine is correct. Thanks all.