[T3] Brake Bleeding

[J. Jonik]

71 Sqbk:   Brakes got to need several foot pumps to work best.Jjust to make sure things were tidy, I made sure rear brake pads were good thickness, and adjusted.  Put a bit more brake fluid in the reservoir, and began a bleed job with a friend on the pedal.
Right rear valve produced just a tiny spurt of air, then just drips despite brake pedal being pushed down hard. Left rear....just drips, also with no squirt.   Front right, same thing. 
  Front left, however, squirted like it's supposed to.
So....is this hard evidence of Master Cylinder trouble?     It can't be, can it, that three out of four of the rubber brake lines going to the wheels all clogged up around the same time.About a year (?) ago I had to replace one of the front brake lines that was clogged solid.  That was probably the one that worked well today.  Are the others just catching up?
Then, IF it's the Master Cylinder...I have over half a dozen of them in my brake box.  All came from cars where they worked at the time the parts were taken.   Is it likely that they won't work after being dry and idle for years?
What's the recommended plan of attack on this job?
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