Do these things ever go bad and if so, what causes it and what usually needs replacing? I was told vibration destroys them but was also told that it's a one-time-buy, never having to replace anything on it.

Thank you,
-Kevin

Only problems I have ever heard of are 1) Throwing the magnets. If you exceed the max rated RPMs, on some models you can dislodge the magnets from the armature. 2) bent shafts from crashes.

Yes, vibration will destroy them, same as just about everything else on the planet. However, you're not supposed to have any appreciable vibration on an electric airplane. If the propeller has been balanced, and the gearbox or motor shaft has not been bent in a crash, you won't see any vibration at all.

As long as you can avoid severe crashes, the motor will quite literally last forever.

You can fry the windings from too many amps also. Ask me how I know

So many brushless are cheap and poorley build LRK is one
they don't balance them.Preload the bearings heatsink the windings. So many things. CU