Can anyone suggest what is going wrong with the gimbal, it seems to be getting worse

Try an IMU calibration, followed by a gimbal calibration, if you haven't done that already

mrbill Posted at 2016-5-18 10:11
Try an IMU calibration, followed by a gimbal calibration, if you haven't done that already

After you calibrate, take a flight.

If the problem still occurs, upload your flightlogs to http://www.healthydrones.com/ so we can take a look.

I think it has something to do with the sport mode the gimbal cannot handle the force generated by flying in sport mode...
What else could it be and the only answer you will likely get is to send it in for repair

Hello k.lower, does this issue happen when the drone is hovering or flying in P-mode?