The fuel gauge stopped working during the time St Piran was getting painted. No idea why, but I didn’t have any time to take the tank back out and see why. The surprising thing was the float wire had come completely out of the sensor, again no idea how that could occur! I tested the sensor and it had failed 😣. Fortunately they are still freely available.
The new float comes with clips to connect the two cut lengths of the float wire. You then use solder to ensure it does not move once installed in the tank. I used Blue sealant to help ensure no vapour could escape the sensor mounting. Most cobra boots have a smell of petrol but not all! Mine did ahead of changing the sensor so I was hoping with the addition of the sealant and a couple additional screw fit connectors to the rubber feed pipe that I would cure that problem! Time will tell!
Hawk 289 FIA AC Cobra Replica - St Piran 
I did mine a while back too – taking it out was a pain. Sensor had become all stiff and didn’t move up and down freely, so I put a new one in. Works now, but bizarrely, the ‘broken’ stiff sensor became loose again about 2 weeks later. No idea what happened there!
Hope your boot is whiff-free!