More power necessary on 1 motor

I have an issue, that wasn’t present till last week.

One motor curretnly needs a higher stick input before it starts to spin. After arming all propeller are turning except the one. With the Motor Test option in the Mission planner i increase throttle to 10% and activate each single motor. That worked perfect for a few weeks, but now one motor starts only with 17% or higher.

Any idea?


Have tried re-calibrating the ESCs? I had a similar issue that was cured by doing that.