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The thread pitch is the same. The only difference is that the thread is much thinner (it does not stick out as far from the rod). As you said, the smaller surface area of the thinner thread reduces friction.

I have done more tests on a fully extended LA, and the bending is no problem. When pulling load, the LA is forced straight (expected) When pushing load, the LA is also forced straight (which is a surprise) When under no load, the LA bends under its own weight. This shows that when pushing load, the LA is shorter when straight, but when pulling load, the LA is longer when straight.

I have changed my vote.

The bending only happens when the LA is fully extended. When fully extended, the friction is not really a problem, because the LA does not need to extend any further. Even when fully extended (and under load), I don't think the friction is any worse than the friction in the older LAs.

The service bag has now arrived, so I have dismantled and compared an old and a new LA. The new LA is almost identical to the old one; it still takes the same number of rotations to extend; it still extends to the same length; there is still a clutch. I have cut the white plastic sleeves into pieces to look at their teeth, and from what I can see, the sleeve is identical on both LAs. There seems to be only one change; the 'tooth' of the screw in the new LA is significantly smaller. Performance changes: -lower friction -the new LA rattles less when extending/retracting -the new LA is much quieter -the new LA extends/retracts more smoothly, especially at high speed Unfortunately, because the new LA has a thinner 'tooth', the new LA bends more when fully extended. The end of the rod can move by an extra mm in each direction. It is not actually as bad as the photo suggests, but is still noticeable. Edit: There is also much more grease in the new LA. Grease has been applied inside the sleeve, inside the clutch and between the orange part and the outer casing. The plastic was also much harder to cut away on the newer LAs (more glue), which is why the two dark grey pieces look different in the picture below.

All of my LAs have '61927' written on them, including the 4 new LAs!