my charging weather cap detached

I'm not sure it is broken. I just got a replacement one arrive in the post, to replace the old rattly loose one, and it comes with little rubber attachments like that with an open circle (2 of them in fact, but I'm sure I only need to use one)

Ah I see (sorry, different user IDs on phone and PC. I need to fix that)

You have to use both and have one flipped over, which mostly closes up the circle. Looks similar to the OP and just needs to be unscrewed and reattached to the rubber post on the cover & then screwed back in to the device.

and they’re not rubber, they’re metal. Needs a 00 precision screwdriver bit.

The Cap should a rubber tail that goes into the clip. I don't see the tail in the photo.

Let me take the door off my unit and take a photo

It might just be the angle of the photo. 

I also have a detached weather cap, but I'm finding it impossible to screw the cap back into place. Any tips?

It’s one of the fiddliest things I’ve done in a long time. I used a high quality magnetic 00 electronics screwdriver, feel and a lot of time and patience. The plastic it screws into feels like soft cheese that’s primed to cross-thread. You can only just turn the door 90° out of the way and have to hold it there if I recall correctly, with the hand holding the unit off the desk as you use the screwdriver in the other hand.

Something like this I think, trying to hold the door steady with 2 fingers.

Thanks for your tip. With my wife's help, I managed to re-attach the cover. What a chore...but success!