I have traced the rattling I hear when printing on my A1 to the vertical piece of metal used to eject a poop post-extrusion.It’s the one with the “teeth” on it in this picture:
When I lightly touch the metal part while printing occurs, the noise stops, and when I remove my finger the noise resumes. I believe I can see the part vibrating during the printing which would likely be the source of the rattling noise. I have a ticket open with Bambu Lan support on this and another A1 issue (severe nozzle dragging). I will try to come back here and provide an update once they respond.