Hi guys, I have bought s900 3 weeks ago.
When I setup landing gear function in A2 the landing gear goes up and the drone go down  at the floor. From this time when I power on the s900 landing gear has a shake and when I take up and down it's not good.

You can see this In this video..

Hope someone helps me..
Thank you..

Just one side has a shake?
Looks like something blocked it. Can you check the screw on servo to see whether it's too tight and lack of lubrication?

did you do the landing gear calibration?