propeller mount

This evening I went to fly and everything was normal. After flying for about 15 minuets I was heading back and the drone started tumbling from about 200 feet. Anyways, the gimble arm is cracked along with the strip of data wires. And one landing gear is broke. One of the propellers was...

Hey Gang, Anybody know which size allen / hex key I'll need in order to replace a broken propeller mount? I've added a couple of these parts to my flight case since they cost peanuts and can make the difference between a successful outing and a wasted trip, but I can't figure out what size...

****** There was a post on the dji forum of a bird that fell from the sky and it looked like the prop clamp screws on the motor had come off mid flight.... Thanks to the posers there and summerised some tips below. ****** So decided to give mine a check.... add this to you pre flight checks...