Do you have a multimeter available to carry out some tests?
Ok, first can you test the emergency stop for continuity when the key is fitted.
Then check if the cables are securely connected at the rear of the console, so that the speed control signal is getting to the motor. You can test the motor signal cable for voltage to see if a signal is getting to the motor ok, or not.
If the cables are ok, then the fault is within the console - either some buttons are sticking on, preventing the speed control buttons from functioning, or the console has an internal fault.
Try rubbing all of the buttons on the console first, to help release any that may be stuck. Rub your finger across the buttons several times, then release.
Let me know if that works...
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yes, there is voltage to the motor, however there is also a control signal - it is the voltage in that signal wire that you need to check. It controls the speed.