Xbox elite 2 controller left joystick has a bump after I sent it to Microsoft to fix the...

I sent Microsoft my Xbox Elite 2 controller for a work order to fix a problem where the left bumper click is not registering. When I received the controller, the left bumper is fixed but the left joystick is bumpy when moving in the right direction. Before the left joystick is completely smooth. How can I fix the problem with the joystick? I don't want to send the controller to Microsoft again since it took a long time and the service does not seem to be that good. Should I attempt to fix it myself and how difficult would that be?

:)