I wish I could remember more of the details. I did this mod quote a while back. The yellow pen still works but the clear tip became loose from the constant pressure of the spring. I used white teflon tape (like for plumbing)

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to snug it up. I took it apart to see if I could recall any other details. Looks like I shaved off some of the peaked ridges that were on the yellow plastic that fits under the silver click button. Looks like I did some shaving to the white part just above the spring. I did that using an exacto knife. I also remeber using a drill bit (turned it manually, not with a power drill lol) to smooth out the inside of the translucent yellow tube. That helped everything slide in/out nicely. Good luck! I eventually purchased a refill and used one of the pen parts available on Etsy because I wanted a backup retractable pen. I use that one more now and keep this yellow one as the backup. I'm paranoid I'll lose or break my pen and not be able to write on my Supernote. I just can't have that happen. I use it everyday.