Just exactly how do these power bleeders work. I have seen some that are connected to an air compressor, but others are manual. Do you open a bleeder screw and push all the fluid out, then bleed the brakes with new fluid?

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member