Hi everyone,
I came across a Reddit post from another X2D owner with the same noise, which led me to investigate the tensioner cover and try a few things.
After carefully laying the printer on its side, I noticed that placing my finger on the Z-axis belt tensioner cover made the noise disappear completely. This pointed to the cover as the source of the creaking.
(Please ignore the green square and the screw inside it. Some X2D printers do not have this screw.)
I tried tightening and loosening the cover’s mounting screws, as well as removing and reinstalling it, but none of those adjustments completely eliminated the noise.
What finally seems to have worked was applying a very small amount of grease to the plastic-to-plastic contact areas: the center of the cover and the ends near its screw mounting points. Just a thin film.
I did not lubricate the belt. It was silent with the cover removed, and I could not see any contact between the belt and the cover when installed. The noise appeared to come from the cover rubbing against the surrounding plastic.
Since applying the grease and reinstalling the cover, the noise has completely disappeared so far.
I’m sharing this as a possible fix based on my experience. It is still too early to confirm whether it will be permanent, but the improvement has been immediate and very noticeable.