I spent much of Saturday evening reading about electric brakes. Everything I read online about this style of brakes said that the condition I’m seeing means they’re due for replacement. The magnets are a wear item and can be replaced with ease. After replacing the magnet, the magnet surface is now flat/smooth and would not effectively transfer energy when pressed against a rutted drum. This means the drum should either be ground down to a smooth surface again, or replaced. Grinding down the side walls is common and shops have the means of doing this. Grinding down the rear, however, is harder and requires equipment not easily found.
It was starting to look like I might be replacing these after all. I started pricing out a repair. At $20 +shipping for a magnet, plus minimum of $30 per drum to grind it down if I’m able to find someone who can do it, and then I still have to clean the whole assembly to get it smoothly moving again. An entirely new hub, bearing, and brake assembly kit goes for $100 /wheel on eBay, shipped. For and extra $50/wheel, the time saved is probably worth just buying a new set. I was going to be placing an order for a new set anyway for the front axle that’s currently brake-less, so why not just double the order. I resigned to solving this problem the way I solved most problems in the days leading up to our move to AK: throw more money at it.