I cut my old one open for a failure analysis and took pictures. The wiper arm and the resistance winding were both undamaged, the main issue was that the winding was dirty. Too much resistance makes the gauge read low on the dash. I was able to test the gauge with a potentiometer before I spent the $164 on the new sender, and the gauge was not at fault. I suspect the gauge rarely fails, as it is rather protected being inside the passenger compartment.
I suspect that the rubber boot around the can plays a large part of why this happens. The canister around the workings of the sender is open to the atmosphere, surprisingly. The rubber boot is there to provide a high-resistance path to dirt and grime, but over time it does not keep everything out. The fact that the resistance winding is apparently lightly greased from the factory means any dust in the air moving in and out of the can collects on the windings.
There is a vent hole in side of the metal can that could be used to spray in some electrical or brake parts cleaner and get the connection between the wiper and the resistance winding cleaned up. It might save you $164.00 to try that first if your gauge is not working right.
Good luck with it.
Chris