Motor twitch issues, copied from official support

FYI, Unofficial support has 100x the potential support base of official support.

19/20 of past trouble shooting reports with similar descriptions to yours, the problem is in user code, doing multiple assignments to the same motor. Look for this, and if you can’t find it, post your code and someone will point it out to you.
Example: three different settings for motor4. oops.
while(1){ blah blah blah if (cond) {setmotor(4,n); } blah blah blah
blah if (other condition) {setmotor(4,y);} blah;
arcade(blah, motor4, motor5,blah);
} //wend

One way to help find this easily is to use Macro/Constants for all EasyC number assignments; Defined M1 as 1, M2 as 2, etc, then use M1 as the motor assignment for all EasyC commands, to help separate motor numbers from the other numbers in the list of arguments.

Another way to avoid it is to use Sense Plan Act coding style, which avoids all use of EasyC commands like Arcade. Sense: read all the switches and sensors to input_variables. Plan: look at all the input_variables and decide what the motors should do and set an output_variable for each motor. Act: setmotor for each output_variable. This prevents multiple assignments to motors during the while(1) loop; you can still have coding errors while assigning the same output_variable multiple times, and feel confused when changing the code for the first assignment doesnt affect motor assignment, because a later assignment is overriding it.

If you post the code, and it is clean, then you’ll need to post a bigger description of “repetitively twitch” and “command to move”.
If you plug spare working motors not connected to mechanisms into ports 4,5 , and disconnect all other motors, and ports 4,5 still twitch, and its not your code, it may be a very unusual hw/sw problem. You could try reflashing your cortex and joystick.
But its probably your code. If you replace your entire code with something simple and the problem goes away, its probably your code.