You can rebuild the wheel cylinders in 5 minutes, there is a $20ish kit at the dealer for both cylinders. If you need pistons there is a separate kit with rubber + pistons for one cylinder. If you push them out far enough to check them you'll get air in and have to bleed again!!

There's a gasket between the hub and drum too, it costs a few cents.

At least you didn't find a brake drum full of oil smile


97 T100 4x4
97 328i
95 540i restoration project