Not my area of expertise, Jacko, but, as I understand it, the valve should default to the HW position when no power is being supplied to it. Assuming the programmer is Ok and the green light means that no power is being supplied in the HW mode, then perhaps a problem with the DC motor. Either that or it's unable to overcome the return spring tension.
There have been problems with cheap Chinese copies of the Honeywell valves. That may well be where the issue lies.
Either fiddle manually with the valve, or, as is usually the case, try another one.
I'm afraid that's all I can offer.