FIMI X8 Inferior prop may trigger Excessive vibration warning - Sep 14

During the flight, excessive vibration warning was popped up while full backward flight (speed set at 16m/s).
I thought it was caused by gust or something.
But expert suggested to check the prop condition one by one to see if particular arm starts to vibrate.
I have been using current props since Apr. ’20 and no damage, chipped off at all.

Did test (suggested way of testing) and observed Front Right arm vibrated.
After replacing unused new prop, vibration disappeared.
So, I believe this is very useful test.
Make sure drone does not lift up when motor running.
Please note that all drone’s screws were tightened before this test.

Timeline is;
0:00 Hold X8 with belt not to moving around
0:10 Manual prop rotation
0:19 Motors payload error, check props
0:22 Excessive vibration detected, check prop and drone body
0:27 FPV screen
0:32 Warning
0:50 Remove props
1:10 Front Left prop only rotating
1:19 No vibration of F.L. arm
1:39 Front Right prop only rotating
1:45 F.R. arm vibration observed
2:22 Checking again F.L. arm condition
2:30 F.L arm – no vibration
2:58 Rear Left prop only rotating
No vibration, only vertically lifting up
3:30 Rear Right prop only rotating
Same as Rear Left
3:51 New props (unused)
4:10 Set new prop to F.R.
4:23 F.R prop only rotating – No vibration
4:58 F.R. set again old prop
5:18 Vibration
5:42 F.R. set new prop again
6:09 No vibration
6:19 Set new props
6:59 Start all props
7:19 No vibration, No warning