I have a straight Case 621 that I bought with locked up brakes. I have put on all 4 rebuilt calipers, and I am having trouble bleeding them. One caliper squirts out the bleeder valve as it should, but the other 3 barely dribble. The reservoir is full of brake fluid. Do I have a problem with the two master cylinders, or something else?
Have you checked all of your brake lines making sure they are not pinched anywhere? Loosen the brake lines at the caliper (not at bleeder) and see if you get brake fluid there, you might have caliper problems. And of course check the air pressure at each master cylinder air chamber.