1. My experience, such as it is, is that the rear brake hose is likely to be plugged. My own personal vehicles have had 3 plugged hoses, and one that may have been restricted 'cause the brakes worked significantly better when the rear hose was replaced while doing other minor brake work.
2. I'm gonna have to dig up a service manual for a vehicle new enough to have the aluminum-body, no-bleeder-screw RWAL. I don't know what the proper bleeding procedure is for them. Current suspicion is to use a scan tool.
3. It's way more difficult and time-consuming to properly bench-bleed a master cylinder than most folks understand. Many master cylinders tend to be tipped with the front "up" when installed on the vehicle. This leads to air bubbles in the front of each piston that don't tend to go down-line and get bled-out at the wheels, but also don't get pushed into the master cylinder reservoir. They just stay in place and cause problems. Ideally, a master is bled with the front end tipped "down".
4. I got my ass handed to me a month or three ago. Guys were claiming that their safety-switch in the combination valve had slid to one side, BLOCKING FLUID FLOW. I told them that this was impossible. The safety switch doesn't block flow, and most GM switches are self-centering anyway (I've seen Ford switches that were not, had to be manually centered.) Naturally, having made the Grand Pronouncement, they then reported that their GM switch had to be manually centered, and when it was held there with the Special Tool, they got fluid flow to the rear brakes. Truthfully, I'm still scratching my head over that.
5. I have no use for "garden-sprayer" brake bleeders made popular by Motive; but sold by many other companies, some of them decades before Motive brought out their product line. A proper brake pressure bleeder has a rubber diaphragm to separate the compressed air from the brake fluid--to prevent the humidity in the air from contaminating the fluid. But those bleeder units also cost real money.
