I have had little to no problems with serious flight times on my first P4. Stable as a rock even in extreme and poor conditions. Not so with my newest one. Test conditions: Open area in a rural area with low to no electrical interference. 83 degrees Partly cloudy Humidity 1% Wind gusts up to 4 mph Pre fight check list all systems were optimum. The problems. I just activated and tested my second P4 today. It is not nearly as stable as my other one. After an hour of us, gimble became increasinly unsteady and erratic. More stable going up than coming down. Calibration pre flight was good. Subsequent calibrations shows good too. Stability was poor in hover mode. Drift issues in near zero wind conditions. What I tried to mitigated issue. Latest firmware updates. Multiple calibrations of gimble only worsened condition. Multiple IMU calibrations Multiple compass re-calibrations. Outcome: No improvement in aircraft stability Worsening gimble operation and stability.