Bertie the A30 fuel gauge stuck on empty

Since he arrived Bertie the 1954 Austin A30 has always shown empty on the petrol gauge. We've been keeping tank pretty full as we fix other issues but this is now top of the to do list. First check was to see that there was power at the B (battery) terminal of the gauge. Yes. Next was to disconnect the T (tank sender wire terminal) of the gauge. With ignition on it then showed full. This proves gauge working as it falls to empty as terminal T is progressively grounded to earth. That connection was put back and the tank sender disconnected, again gauge shows full so no ground fault along the length of the sender cable. Pulled the Sender unit out and the video reveals the fault caused by a very long period of inactivity.
POSTSCRIPT: The float cleaned up nicely. It wasn't rust as such just sort of crystallised fuel residue. Some WD40 got the float arm moving. Put it all back and hey presto a working petrol gauge, probably for the first time in decades by the look of things. Next up a look at the lever arm dampers, particularly at the rear, that seem to be doing very little to calm down axle bounce on rough surfaces. PS the gauge sender worked fine when refitted but a further test run ran into fuel starvation when it was found that there is a gauze strainer inside the tank that cannot be serviced had become choked. It has been cleared using high pressure air line. Tank also flushed out several times to remove loose particles. Now seems to be running noticably better.