Thanks Doddy!

Following your instructions, here's what I found: with the PC turned off, the moment I turned on the system, the LED next to the 'PC Power' terminals came on and the voltage between them was 1.8V. When I turned on the computer, the LED went out and the voltage also disappeared. I remember that a similar situation has happened more than once before and I could not figure out at what point LED was disappearing, now I know. I turned off the computer, turned off the system, waited a few minutes, turned on the system again - PC LED was no longer on, no voltage as well. I repeated the process again, this time I waited longer, the result was same, no voltage, no LED.
Then I wired +5V & 0V. At the time of connecting the LED output diodes ‘blinked’ sending a few short pulses (without the use of software) to the motor but the 'outputs status' LED disappeared, which is not desirable I’m guessing? So now, with 5V wired to PC Power terminals ‘output status’ LED is permanently off.

With such behaviour, do you think that it might be a time to think about the new BOB or perhaps something more to check?