Placement of the geolink next to magnetic motors has come up as a issue. Different servo motors have different servo strength. Some servos may need the geolink places further back on the tail.

Can you show which direction is north on the geolink app? Then if you turn the heli you could see if north stayed in the same direction or turned with the heli. This would be a clue the geolink is to close to a magnet.