Cleaning a piston filler in ten minutes
No special kit, no disassembly. Just a glass of water, a soft cloth and a little patience.
Flush your pen whenever you change ink, or every four to six weeks with the same ink. Dried ink is the main reason pens stop writing well.
The routine
Expel the remaining ink into the bottle. Draw up room-temperature water, expel it, and repeat until the water runs clear. Leave the pen nib-down on a folded cloth overnight to wick out the last drops.
Iron-gall inks like Iron Indigo need flushing more often. Never leave them sitting in a pen for months.