A Key cap has fallen off. How do I refit it?

[pnts-se]

I have the same problem with key "A" I can out bck in but it it a bit loose and pops out after a couple of presses.

Not an ideal user experience!
I notice my 'tab' key is sometimes sticking down, on its top right corner, if I don't press it centrally. I really hope this isn't a warning sign.
I love this device, aside from the keycaps issue.

My tab key has come off two times. Not the plastic hinge, only the key.
Not sure if I press it on the edges but I'll pay more attention from now on and try to press it centrally.
I've managed to press the key gently back on both times.