Holee Molee.
Something so simple. Remove drum, pop the bearings out, clean bearings, races and EVERYTHING shiny clean. No seals! Reassemble. Loosely. LOOSELY! If the drum turns out of balance, use MAG WHEEL WEIGHTS, but epoxy them or JB Weld them to the drum until the drum is reasonably balanced.
Pop the drums off again. Pack the bearings, pound in the seals, and reassemble.
Yeah, you can go further and mount the tire to the lubeless drum bearings, and balance the tire that way too. It isn't spin balancing, but I can tell you it works just fine for low speed trailers.
