If the stick off centers (in the HUD test software ie) then it is a hardware problem - caused by a “mechanical play” (click pic).
THIS particular issue is a reason why i personally came up with this solution (mod)
If it is a constant “bank” or “trim” input, then it is either a hardware problem - which can be checked for false inputs in the control panel of Windows -
or it is really just a conflict in your BMS input key-assigments.
As this constant “bank” or trimm happnes randomly …it almost sounds like an unintented electric contact (wires torn off ie.) causing a false input
or 2 device-axes assigned as “roll” axis on jet - thus conflicting.
IF everything is “ok” in your device-control application (outside of sim), then you are lucky…because then you don´t need to send it back to warranty appartment as it is not a hardware issue and we can start localizing the issue inside BMS. I also can sent you my DX x55 assignments with enough pictures and elaborations …but then i first need to know if windows pics your x55 up as device 1 or device 2, so i can adjust the values in the key-file before i sent it over to you as a test-plattform (as you can see in my case stick is device 2 and thruttle device 3 as my rudder pedal is device 1 in OS).