Sometimes replacement parts just aren't available for old cars, especially really old cars. This 1931 Plymouth fuel level sending unit was non-operational and there were no replacements around, so that means I have to tear into it and see if it can be fixed.
The inside was very rusty and corroded. The old cork float was in bad shape as well.
Luckily, fuel senders are really simple devices, so they can usually be fixed. The gear at the bottom of the shaft was loose and had to be re-soldered in place. The "clocking" of that gear is how you can change the calibration of the unit.
Everything was glass bead blasted and painted with black enamel. I found some brass rivets to match the originals and cut a new cork mounting gasket. The float is from a kit for a model A ford. The electrical contacts inside were coated in dielectric grease before reassembly.
I used an ohmeter to check and adjust the operation and calibration of the sender. This is a critical step, because you have to make sure it operates accurately.