[PeteLeathersac]

Obviously you've cleaned and serviced everything, LH/RH adjusters also longer shoes all correctly placed plus emergency cables free and released...wind out rear adjusters 'til you can just get the drums on but not dragging when fully in place and rotated.
When all else was correct and new masters seemed to be at fault, we used to give them a few hits w/ a hammer while someone else pumping...sounds dumb & not what you'd want to do to resto cars now but it often made wonky masters come around also stay Ok after you got good pedal.
Good luck!
[img]<<GRAEMLIN_URL>>/beers.gif[/img]
~ Pete