The bottom post for one of my lights fell out. The nut fell off and was behind the fixture. Sans the washer. I used a couple of my own to repair. There was virtually no slack in the wiring as a lot of careful pulling got me to where I could repair. Thought I’d take pics so you can see why it looks like in case you encounter this ..
(I have the bolt positioned backwards here)
New washers installed
I used another fixture to compare where all the spacers go (there are 8; 10 if you count the two pairs mashed together that form one). Fortunately I didn’t lose those behind the sofa.