Your rowing machine monorail: does it have black residue? Here’s a quick video on how to clean it. We recommend using a household cleaner or glass cleaner and a paper towel or rag. You can spray the rag first and wipe down, or the rail itself. Be mindful to not spray the monitor directly if cleaning other parts of the machine. Go to https://www.concept2.com/service/indoor-rowers/model-d/maintenance for more maintenance tips! #Concept2 #RowErg | Concept2, Inc.