[Walky]

If you take the nut out the balls will fall off, you can put them back but it can be a PITA.

You could try removing the seals and injecting grease through the grease fitting while moving the nut around the screw, some debris might go out at both sides along with the grease. Another way to put grease on is to remove the seals and put grease on the ball grooves on the screw, then move the nut along.

[superagurk]

Ok, thanks!
Not sure if I dare to unscrew it, but removing a seal and pump some grease in could solve the problem.

The scratching sound appear once pr revelation, and seems to be louder when nut is moving one way compared to the other.

Andreas