86 4kq master cyl question

Greetings

It's been quite a while since I stopped in here to ask a question. Did
manage to change my timing belt and also rebuilt my front end last fall.
More recently, in the middle of a coold January, it was an alternator
replacement.

Question is: if I can't pump anything out of the bleeder on the
proportioner (term?), is it a sure thing I've got a bad master cylinder?
I also replaced a caliper last summer and never did feel like I had the
lines bled perfectly. Brakes got worse this winter. Last weekend I had a
helper so I tried to bleed the lines; my helper said the pedal response
was erratic--sometimes it would firm up, and the next push was mush.
I've got brakes--at the very end of the pedal travel. At the bleeder on
the proportioner, neither can I push any fluid through with a pedal
stroke nor can I pull any through with a vacuum pump.

Gotta be the master cylinder, right? Clogged galleys? Say goodbye to
$200?

miguelito