light cut of ammonia in water and soak , then flush and repeat, a baby flush bulb, can get in pharmacy for like $2 helps too, ultrasonic good for really old pens that are have decades old gunk in them but not completely nesc with patience, don't use hot water may warp something , stuff some paper towels in a coffee mug and dry tip down , for new pens if you test it, a quick flush will leave it fine for the next use , it's ok to leave ink in a pen for a while but for extended periods best to flush , some inks may have acidic properties that could damage the internals over time
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