Update: Here's what we've seen on this latest batch of headlights
Carlos had a chance to look at the latest batch of headlights, manufactured in December 2023.
The aiming adjustment mechanism has changed slightly, in that the "leadscrew" has a slot it in that can be used to hold it stationary (the lead screw) while adjusting the aim.
("leadscrew" as referenced in Wikipedia:
https://en.wikipedia.org/wiki/Leadscrew)
Ideally the leadscrew would
not turn during aim adjustment (meaning, it would remain stationary on its own accord, it would not need to be "held stationary") but in the past on some Arteb headlights it
would turn, and evidently on this latest batch it
may still turn. The fact is,
it must remain stationary in order for the aim adjusters function. Users in the past have managed this by lubricating the leadscrew / aiming adjuster, e.g., see this post and others following it:
Adjusters: Introduction and inner workings I'm creating a couple of posts to acquaint owners with the adjusters and how they can be lubricated (find the later post here https://www.gmt400.com/threads/arteb-brazil-gmt400-headlight-users-thread.56596/post-1234731) Attached is a set of annotated...
www.gmt400.com
My take on it is this:
(1) Aiming these headlights is crucial; their headlight pattern is EXCELLENT but they need to be aimed correctly or the excellent pattern won't mean a thing.
(2) New owners should plan to spend a few minutes lubricating the adjusters as detailed in the post referenced above. The slot which Arteb has recently provided in the leadscrew will facilitate holding the lead screw stationary during lubrication.
(3) There are two adjusters on each headlight housing (four total, for a pair), and each has its own leadscrew. The leadscrews on one housing are pictured below, and more extensively in the post linked-to above.