Good Day Folks
I have a quick question about the captive nutts (which can't be seen) that hold the window panes (pains, lol) in place in the doors. There are four of them and two of mine just spin and are not able to be tightened. From feel, it's like they are in some sort of casing rather than a weld and they just spin inside of the casing/surround.

What do they look like from the back/inside and does anyone have any experience or possible solution for getting something on them, in there or replacing them?

Need some guidance here.
As always, many many thanks!