HP LaserJet Enterprise flow M830 Multifunction Printer series - Manual (Page 186)

Send to a different fax machine
Try sending the fax to a different fax machine. If the fax quality is better, the problem is related to the initial
recipient's fax machine settings or supplies status.
Clean the pickup rollers and separation pad in the document feeder
1. Lift the document-feeder latch.
2. Open the document-feeder cover.
176 Chapter 9 Solve problems ENWW