A few days ago I replaced the dragging LR brake caliper, but I had a heck of a time bleeding it. I took the cap off the reservoir and saw fluid at both the front and rear compartments.
I had my 5 yo pump the pedal, but I could not get any fluid out! Even when I disconnected the hardline from the caliper no fluid came out. Hmmm....

Thinking the reservoir's outlet is blocked I removed the rear level sensor to find no fluid! Apparently each compartment (front and rear) inside the reservoir is further divided into 2 compartments, and the one close to the fill neck can be full, while the one that connects to the MC is empty. What a weird design...

Csaba
72 280SEL 4.5