If you happen to be using printers from the HP 600 series, HP M601, M602, M603, M604, M605, M606, M607, and so on, and the printer is sending out blowbacks for which the ink is too faint for legibility, consider that there may be a mechanical problem with the printer that a layman can fix.
Today, when I sent jobs to my HP M601 printers, I consistently got print-outs for which the ink was very faded. So for example, I was getting print-outs of the quality of these on the right, rather than those of the more standard quality on the left.
Under printer preferences, on the Paper/Quality tab, if EconoMode is selected, try unchecking this box and attempting to print out additional pages and see if you get a better result.
If this doesn't help, check and see if your HP printer includes an option under Printer Preferences on the Services tab under Device Servies to clean the printer.
. . . if no such option is available, open up the front of the printer and remove the ink cartridge. Check and see if a roller bar like that in the below photo is loose. This padded roller bar with the light blue cog and a black piece of plastic on the left side, has a tendency to become misplaced when the printer is moved. If it is not in the correct position, printouts may come out too light.
Without any special tools, you should be able to position this roller back in place like this:
Slide the knob at the right end into the slot in the white bracket affixed to the printer, and then place the opposite end with black piece faxing down.
Tonight, I shifted this roller bar back into positition, and the HP 600 series printer printed out hard copies at an normal resolution.