So I was putting new shoes in the rear and I wanted to flush the brake fluid as it hasn’t been done since before I owned the car. Both front calipers went fine then on the drum my bleeder screw broke off. I tried to block it off while waiting for a new bleeder but everything drained out anyway. Now that the system is dry it seems that I need to bleed the master as well as all 4 brakes. Do I actually need to bleed the master and if so how could I do it in the car