I had a leak in the rear brake line so I took the old one out and installed a new section. When I started to bleed brakes I found that the rear bleeders would not work. Through investigation we learned that the lines on the rear axle were not getting brake fluid starting where the line changes from metal to rubber. I was hoping for ideas on how to procede.
The rubber lines can swell internally, especially if the fluid has been contaminated but that usually shows up as not releasing. The master has enough pressure to push right through it so I really doubt that you have an obstruction.