Brake issues

[WmPMay]

I have a 1984 G1200A, runs great. Issue is brakes lock up. Need to crack the front of rear bleeder to get bike to roll again.
I rebuilt front / rear calipers and master cylinder. installed new rubber hose on rear.
On master cylinder I plugged front brake then plugged rear brake lines to isolate which part is not releasing pressure. No luck. Everything points to master cylinder.
Take MC apart again and verified all parts are correct. and all ports are cleared.

I'm at a loss.
Any idea.

 

[julimike54]

The very tiny return hole in the master cylinder needs to have a small gauge wire run through it (small think E string). There is a small flat disk that is over the hole, it's removable for access to the hole.