Wow, thanks. This is the answer I was looking for, how to get ink to the gimmick, not just the sharpie itself.

I've had three. With one, the tip fell out, fortunately just AFTER I had used it while filming for the BBC. Not that it mattered, because after replacing the tip (if you get one of those retractable pentels and cut the ink tip off it fits perfectly) the darned holder broke. Boink - straight in the bin. However, on complaining, this was replaced free of charge - great service. I had already bought another by this time - and the caps on these are VERY tight - might try the sandpaper idea. I like it because it got me out of a really messy situation once - definitely worth having it nearby!

Drew

I regularly sit down and write sentences with both the gimmick and the pen. I practice numbers, letters, shapes. Round forms still trouble me. It gets better after a week or so. Practice is also a good time to make sure that the thickness of the tips match. I push the gimmick on a flat surface, but careful it is easy to overdo. Also be careful not to mess your fingers during the handling. In the early days, somebody got suspicious because my fingers had small dots on them.

I prefer painted cheese wax instead of the tack. It keeps the paint longer.

I like it for the fact I can use a sharpie marker which is more organic than a pencil nowadays.