Coombs' test involves taking a blood sample which is checked for the presence of antibodies which may destroy red blood cells.
You can use the HP Print and Scan Doctor to test the status of the printer spooler, print queue, device manager, and device conflicts. 1  On the desktop, double-click the HP Print and Scan Doctor icon to open the tool. 2  Click Start on the Welcome screen. 3  Select your printer, and then click Next.  Click Fix Printing.
NOTE: HP Utility is located in the Hewlett-Packard folder in the Applications folder at the toplevel of the hard disk. c. Select the HP Officejet 4630 series from the list of devices at the left of the window. d. Click Clean Printheads. e. Click Clean, and follow the on-screen instructions.