Whilst pondering ways to make a linear motion assembly thinner I pulled out one of these old ballscrews to look at, I'm the kind of guy that thinks much better with something physical in my hands. Whilst idly twiddling it and looking down the end of the nut I noticed there was a definite gap in the line of balls if you held it horizontally and rotated the screw, you could hear the balls tipping over the crown of the screw as they made their way down the other side, sometimes accompanied by a sudden roughness is the rotation force. If you held the screw upright this didn't seem to happen, presumably gravity was sorting things out. This made me think, shouldn't there be a more or less continual line of balls??? could this be why they still felt rough after quite a bit of cleaning out of swarf?? Any advice from linear motion experts would be very welcome.