I have a rear brake master cylinder that I think may be at fault for my lack of brake pressure, but how can I confirm it? Does anyone know of a way I can test the master cylinder to confirm it's hosed, or rule it out as a possible problem? I have two different brake calipers, I have went through both of them over and over, the line is clear, the banjo bolts are clear, but I still cant seem to build up pressure on the line.