It is possible that there is a problem with the fault printing mechanism. The following steps will help you to troubleshoot HP Officejet Pro 8600 printing problem:
Once your HP Printer is on, wait till it is silent.
When the printer is on, unplug the power cord from the outlet and then disconnect the power cord from the printer.
Wait approximately 60 seconds.
Now that you have plugged the power cord back into the outlet, you can reconnect it to the HP printer's rear.
Finally, turn on the printer and wait until it is silent before trying to print again.