I just got finished bringing my old Marvy Markers and Brush Markers back to life while posting here.
Here's an example of the Marvy Marker.

They currently sell for approximately 5 bucks on Amazon. I own maybe 50+ of these, so do the math and you'll soon see why I attempted re-inking them. I think this would work for Tombow or any other dual tip water based marker. Actually, Stampin UP sells bottles of re-inking ink on their website.
Save your self some money and try this.
One part vegetable glycerin : one part water in a small container. You need an eye dropper.
Yank off the fine tip gripping the base of it with small pliers. Here's a shot of the fine tips:

Place about 3-4 drops of the solution into the end of the pen. It's got an ink cylinder inside that will absorb the liquid. Put the tip back on with the pliers. Put the cap on. Let it sit upright or horizontally. Overnight would probably be best.
I just saved myself a ton of replacement money!
