Hitting the ground with a drone is not healthy. For pilot’s self esteem and UAV both. Specially when impact’s force will be taken by one of the motors. Most probably it will survive, they are quite tough little devices, but delicate bearing will take punishment and might wear off. Luckilly, signals of damaged bearings are easy to notice: motor starts to make strange noises and you can hear oscillations during maneuvers. At this point you have two options: replace whole motor, or replace bearings.
I faced this situation last weekend when one of my MT2213 935KV BLDC motors stated to rattle in flight. It was very hard to notice in hover, but audible in turns. So I had no other option and decided to replace damaged bearings.
There are many tutorials on that in the internet. I specially liked the one below. I is simple, covers most of the aspects and gives good idea how to do it.
The whole process took about 15 minutes The biggest problem was how to put new bearings into place. I intended to go to hardware store and buy long M3 screw, nuts and washers (MT2213 has 3mm shaft, so M3 screws fits perfectly), but then I realized that shaft from my props ballancer is also M3, so I used it to push bearing into their mounts.
And so, instead of paying more that $12 for a new motor, I payed $1 for new bearings and learned a new thing. Yay for me!
For those who would like to replace bearings in their MT2213, quick tip: this model uses 3x8x4 bering size.