If the drum refuses to budge after a fair amount of massaging, the whole hub assembly can be removed. Pull the 8 bolts holding the axle shaft in, smack the center of the axle flange with a hammer, and the axle will pop out. Then remove the two big nuts on the end of the rear end load tube and slip the hub, drum, and all off. You'll most likely have to do that anyway to change the grease seal at the inboard side of the hub and inspect the bearings. It's possible you're leaking grease as well as brake fluid.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!