both of those spacers should be screwed in place tightly. Their function is to act as a stop, preventing the Z-Axis plate from going off the top of the carriage. They also serve as part of the mounting structure for the Z-axis homing switch if using the Carbide 3D kit.
On the subject of those spacers… What’s the official threading of them? They seem to be 10-32 but only for a half turn…
They were Imperial in the original version, now they’re metric. Notes on it ought to be here: https://www.shapeoko.com/wiki/index.php/B.O.M.
“Aluminum Standoff, 1/2 OD × 10-24 Thread × 1” Long” ?
Yep, that’s it — if someone knows the new specs, please let us know or update the wiki page.
Thank you for your wealth of knowledge!