[Radical Pi]

Huge flaw in your code. Here's a hypothetical situation based on the first one shown:

Button is 6 is pressed. The motor is set to 1.0. However, almost immediately after that, button 7 is checked and most likely set to 0.0.

Here's what I think you want:

if (ThirdStick->GetRawButton(6)) {
    ArmRelease->Set(1.0);
} else if (ThirdStick->GetRawButton(7)) {
    ArmRelease->Set(-1.0);
} else {
    ArmRelease->Set(0.0);
}

Also, I assume you mean if instead of while in that second code block. That version would only activate button 7 mode if button 6 was pressed