Last year I set to revive a BII that sat for 16 years. When I got to the brakes I had no fluid getting to the rear. Both sides rebuilt. Both bleeder open. I could only get a drop or two to come out. Fearing rupturing a rusty line, I hesitated standing on the pedal but finally put both feet on and smashed it. What ever was blocking it finally came loose and my feet hit the floor. Bled clean fluid through it and all has been fine since. My point being they can block up. Keep us updated. I hate stories with out an ending.