Okay, so John,
I ran the code you sent me, as written, and this is what I got
0 0
¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿
I'm not sure if this is the same but, I did check the PWM between channel 1 & pin 10 and channel 2 & pin 11 and I got similar numbers to the ones you mentioned on the Serial Monitor, or close to those numbers, but I'm thinking that's not the same thing.
Still, when I tried to turn Right (ch_1 = 10) or go in Reverse (ch_2 = 11) on the actual robot, using the right gimble, I got nothing; only Forward and Left (or Spin Left, since both tracks are spinning0 are working.
Thank you again, John
PS
While I have your attention, and I'm not sure if this question belongs here so if it doesn't just let me know where I should post it.
Due to the nature of the robot's design, every time I need to access the USB port on the Arduino board I have to remove the chassis.
I would like to permanently attach a short 3" USB cord to the Arduino's USB port to give me easier access to it and avoid having to remove the chassis every-single-time.
So, can I run the robot with a USB cord still attached (not connected to the computer) while powered by another external power supply?