Lexmark 4136 printer has stopped printing, comes out faint or blank

Have you changed the cart and checked or can try cleaning the cart,

# Hold the cartridge upside down, with the bar-code label facing you and take a damp paper towel.
# Use the towel to wipe the printhead of the cartridge on the bottom (where the ink comes out). Wipe the printhead horizontally in one direction only (left to right).
# Continue doing this until it looks clean.
# Then dab the cartridge on the towel to make sure the ink is flowing.
# Next, look inside the printer and locate the carrier that holds ink cartridges. Caution: Make sure the cartridges are not installed at this point.

1. Look for a shiny piece of metal underneath the contacts at the back of the carrier.
2. Take a damp cotton swab (use water only!) and wipe along the bottom of the shiny metal piece. Note: You may need more than one swab.

# Reinstall the cartridges, making sure you snap them correctly into the printer.