Since the last flight my Zenmuse H3-2D comes up with a high frequency sound which is very irritating. It mainly appears when the copter is in a horizontal position. You can hear it here: http://youtu.be/hHAgR8au3rA As you can hear this is not a very nice sound. Any idea what could be wrong? Before I never had this problems (about 10 flights with Zenmuse before). Thanks!