Gather the pen, ink, water, paper towels, and a small cup
Remove the cartridge from the pen
Empty any remaining ink from the cartridge
Rinse the cartridge with lukewarm water until the water runs clear
Let the cartridge dry completely
Fill the cartridge with the correct ink using a syringe or eyedropper
Avoid overfilling the cartridge
Reinsert the cartridge into the pen
Reassemble the pen
Wipe off any excess ink
Test the pen on scrap paper
Repeat cleaning if ink flow is still weak