Looking for a replacement for the ConceptD 7 Ezel Stylus

Hello!

There are a number of threads here that are close to what I'm looking for, but nothing *quite* right.

I'm looking for an exact replacement for the stylus for my ConceptD 7 Ezel. I'm aware that I can replace it with a wide range of EMR pens, but I really want to continue storing the pen inside the laptop. I find that feature extremely handy (even if it is a bit minuscule and hard to hold).

I've found a number of third-party parts sellers. Is there an official site? Are there certified resellers?

I'm also having trouble pinning down the part number (or numbers) for these pens. Thus far I've found "NC.23811.074". Is there some way to confirm the correct part number before I buy?

Any help would be greatly appreciated. Thanks!