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.
HP Printers - Print Jobs Stuck in Print Queue (Mac) 1  Click the Apple menu icon (), and then click System Preferences. 2  Click Printers and Scanners, Print and Scan, or Print and Fax. 3  In the Printers and Scanners window, look at the list of devices on the left side.