Balls.....

I replaced the stock ball bearing for a ceramic (Si3N4/Silicon Nitride) on my HW-19 MkIV using the stock thrust plate years ago. Made a significant difference by being more open/transparent, tighter bass. Just as important with that was the type of oil used and the amount. I ended up using 4 drops of Motul dbl ester/5w40/4T. This was after trying several types of oil/grease.

He is referring to Steve at VAS, he also does business through ebay  as VAS, he retips, rebuilds and builds cartridges as well as the bearing replacements. I have used him a few times and am very satisfied with his work. Enjoy the music

Thank you slaw for sharing the your real world experiment as well as the results. It seems a no-brainer for the cost/benefits received. 

I did a number of transactions with Steve some years ago when I was running VPI, reputable business.

www.bocabearings.com

Should be able to find it here.