I vote for pulling hub and drum as one peice. Most likely the shoes are rusted out against the drum, or a ridge catching. You can try to adjust in, but most times the adjusters are all stuck and rusty if been setting awhile. I have gone as far as cutting off any little mounting heads on back of backplate for holding shoes, then removing screws for the cylinders so they can drop away, pushed away or come off with drum. I have little luck removing the 3 screws, they are usually stuck. I have had to chisel some out carefully to loosen. Then the hub needs to be cleaned good and where they meet is thin space that rust can gather. I have scraped rust out there with a sharp instrument or knife, plenty of penetrant and around the studs too. As noted, the whole hub/drum coming off is still easier. Pull the axles, remove both lock nuts and outer bearings, then hub may move around more to work itself off. Big hammer is a must too, be careful you don't beat drum to death. A heavier 2 to 4lb hammer is better than small one.
