Just got the old girl out from under the cover and found there is nothing going on with the rear brake. Fluid was full but a little off-color, so I decided to change it just in case. Cleaned around the reservoir and the bleeder valve, popped the top and cracked the bleeder, and the pedal goes to the running board with no movement in the fluid level. Tightened up the bleeder and tried to get some pressure to build on the pedal, but nothing doing. Am I looking at a master cylinder problem, or have I missed something completely here?