I'm presuming you have turned the Analog Spindle DAC on in Config Plug-in.?

Output 4 is obviously working as it's LED is lighting so just put a continuity test across the pins and it should toggle ON/OFF.

Aftet that then I'm at loss to help from a far.!! . . . . I'd be very surprised if the controller is faulty but suppose it's possible thou would be a first to me and I've fitted a fair few now.!