. . . and once you have established which end is up, look on the bottom of the caliper body castings. There should be two match marks in the form of "divots" in the castings of the caliper halves, opposite of each other. At times, these markings can be a little indistinct, but once you know where to look they are readily spotted.

If the caliper halves are not matched properly, the the outer, bottom cylinder becomes a dead end which is absolutely impossible to bleed.

One time, before the good people of this forum informed me that it was not unheard of for rebuilders to assemble calipers incorrectly, I spent a week from hell trying to isolate this problem.

Rich