I recently changed my 2 front brake hoses for safety reasons (25+ yrs old ). My 68 SkylarkCustom350 has manual drums all around with no issues. I bled the fronts using a friends power bleeder and it did the job nicely. Having the power bleeder and in recent memory not having bled the rears in a long time figured why not do the job correctly & get rid of the nasty fluid in the rears. Surprisingly the rear bleeders didn’t put up fight, opened the master and hooked up the machine to the passenger rear screw. It sucked fluid for 30 seconds then nothing. Ditto the other side. The car was jacked up in the rear for access. I thought maybe the master being lower than the bleeders might be the problem and raised the front higher up-.no good. Put car back on ground & pedal is spongy . Opened master lid tapped brakes lightly the front reservoir is gurgling, back reservoir nothing. Prior to this brakes were normal - any & all thoughts welcomed .