my 51 cranbrook fuel guage goes up to approx half way and thats all its ever shown since I owned it. Today I yanked the sender out and via moving the arm found that the sender itself was working but the floats were soaked and heavy.
They were two pieces of round cork that looked to have been shellacked or something used to seal them who knows how long ago. (They look vintage and if you look at 'em just the right way, on one you can see a staining of the virgin Mary and on the other one Abraham Lincoln, I'll sell em, just sayin')
I of course dont have a shitpile of cork laying around, but I do have a weird assortment of used brass carb floats, so I strapped one to the arm basically laying the same way the cork was and BLAMMO, my guage works properly now! Yippee