Any suggestions what to use to replace the lead with in a Vernet Swami writer- one with the thicker grease marker lead?

The one I have was a pain to replace until I found a certain brand of china marker at Michael's. Don't remember the brand, but it was the right thickness and consistency and works great for me. I know I have the markers themselves at home, I'll see if I haven't gone so far down as to have lost the brand on the side.