Loose hardware

So early July I found a lock washer on my XCPs work surface. I saved it and on brief inspection wasn’t able to find where it came from. Fast forward a few more projects and even more of these pieces have fallen, so this time I used an inspection mirror to find out where it’s coming from. Some wagers and nuts on the spindle housing are backing themselves off. Keep and eye out, and has anyone else noticed this issue? I’ll include pictures.

Sorry not the spindle housing just the part of the gantry that for the Z axis.