Originally Posted by ferider
It's easy to relube. You can open the focus mount by hand - just twist the curled ring on top of the mount.
I'm not pretending to really know how to work on lenses, but my experience with a collapsible cron was a bit more complicated.
I received mine after a relube from Youxin and it was still a bit sticky, so I tried to solve the issue. I opened the three screws on the lens flange, then unscrewing the flange (make a sign where it disengages). I cleaned what I could, but it still wasn't good. I asked DAG about his opinion, and he told me that there is another area of friction, and if cleaning the helical wasn't enough, a more advanced dismantle was necessary. I decided to send it to Don and (after a loooonnnnng wait) got it back.... perfect.
The thing is with these lenses that the focus movement may seem ok, but it really needs to be super smooth for the user to make small focus adjustments.