Just got my Normcore v4 today. Yes, I had that grinding noise too. I've since polished the internal parts with 2000 grit paper and it has made a difference. I'm sure I can go even smoother if I decide later that it's warranted.

Interestingly the top stud on mine is aluminum rather than stainless, which is likely a good thing since aluminum and stainless don't play well together.

I do think that a slightly longer bottom stud would have helped keep it's alignment with the core sleeve tighter, and resulted in a smoother action.

Overall I'm impressed by the parts you get for the money. I'll be interested to see if performance matches the quality of the parts.

Edit: It's smoothing out with use. So far it's easy to use and does it's job which means there's one less thing for me to think about.

mycatsnameisbernie wrote:My replacement sleeve arrived today from Normcore. It shipped with a new top spring and 25 lb. inner spring as well. Visually I couldn't see any difference, but it does appear to slightly reduce the grinding noise, and the noise that remains sounds less destructive.

I continue to be very happy with the V4, in spite of the grinding noise. Whatever wear is occurring that results in the noise, I think it will take 1000's of tamps before any excessive wear occurs.

My V4's replacement shaft, spring and sleeve arrived today. I can confirm all of mycatsnameisbernie's findings above. I'm also very happy with the V4 and Normcore's customer service.