Rancilio MD-40/50/80 Lower Doser Star This star-shaped indexing wheel inside the doser meters out a consistent dose of grounds with each lever pull. COMPATIBILITY Fits: Rancilio MD-40, MD-50, MD-80 dosers INSTALLATION Moderate difficulty - requires opening the doser body. PRO TIPS If your doser is delivering inconsistent portions - too much on some pulls, too little on others - a worn or chipped doser star is a more common culprit than people expect, since the star's points are what actually meter each dose. Inspect the points for rounding or chips before assuming it's a spring or lever adjustment issue.