The below is from the DJI Mini 2 sales blurb of what you get.
Why would I need 18 Spare Screws (don’t go there!)
In the box:
Cheers guys
Mike
For when the pesky little propeller ones get lost or you shear them 
You need 12 of them for the 3 pairs of props. If you replace props, use new screws. I’m fairly sure they are coated with Loctite Blue to hold them in place. Unscrewing them breaks that seal hence using new screws.
The other 6 are spares in case a screw feels loose but doesn’t need a new prop. Not forgetting the ones you drop & lose trying to replace a prop.
You’ve got me thinking there if I had a spare set of screws with my Air 2. I’m sure the props are replaced as a pair not as single blades. I must check that in the morning.
Be grateful you have them, I didn’t get any screws with my More Combo!
CORRECT, you should never reuse screws once you have taken the out and should always use new, as they are coated with Loctite as you… and it is always better to have too many spare screws than to not have enough. Believe me, they are very easily lost
@Andy601960 Well I’ve learned something there. I’ve never looked that closely to the actual fittings on my MA2 which seem to be a rivet type of non-removal pin so thought all props would be the same.
So, am I correct in thinking that you are able to change just one blade (using a new screw) if required? and do you have buy new DJI screws when you’re out or can you re-use as long as you also use thread lock?
MA2 has push/twist fit props, so no screws involved. You have to replace both props as they come as a set of two connected to a central fitting, For the DJI MINI 2 YOU should replace BOTH props in whatever position the damaged one is and use new screws. New props can be purchased and come with screws, usually more than necessary. As for suing loctite on the old screws, that’s entirely your decision, but frankly I would use the screws provided
I wonder if Loctite 242 blue can be used for medium strength thread locking if you’re in a fix (pun intended) and need to use an old undamaged screw? Its designed to prevent threads from loosening from vibration but allows screws to be removed with hand tools.
I don’t own a mini, are the screws into plastic or a metal insert?
Loctite 242 eats plastic.
The threadlock on OEM screws is probably plastic safe and will contain minimum amount of solvents as it’s part cured.
I wouldn’t put loctite anywhere near plastic.
Both the screws and the screw fixings in the motors are metal. The threadlock would also be clear of the props.
Loctite can be messy and even a stray drop or residue will seriously weaken plastic.
They do a plastic safe 425 that is cyanoacrylate based but lower strength.
I use the blue 248 stick at work where contamination is a risk.
I’d probably use that over the 245 near plastic. It will still weaken plastic but less chance off accidental contact.
Good to know. Thanks. 