How can I fix my actuator?

I suspect that the actuator on the motorised valve (BGMVSP-23, aka Drayton MA1) is broken and would appreciate some help on what to do next.

When central heating (CH) is turned on at the timer (and room thermostat is set), the manual lever on the actuator is in the H position. However, when I then turn on the hot water (HW) as well, the manual lever moves ever so slightly but never at the mid-position. When I only turn HW on, the lever doesn't move any further and is stuck, so doesn't move towards W position. I tried manually moving the lever, but it doesn't seem to budge. I'm guessing that my room and cylinder thermostat are working fine (heating works and I get hot water from cylinder if I heat it using backup electrical supply), so I'm guessing the actuator head rather than valve is not working?

I have subsequently removed the actuator head and began dismantling it as I thought the motor is not working. However, when I tried to disconnect the old motor, the pins on the PCB (or whatever you call it) came off the solder joint so now my actuator definitely doesn't work. How do I now know for sure the motor is working/broken? I'd rather fix a faulty motor rather than forking out on a new actuator if possible. When I removed the motor, the lever could be moved from side to side and always sprung back to the W position, I guess this is normal? Even when gears on motor is in place (but motor not connected because of the faulty wiring), I can move the lever from side to side and hear the gears moving.

I've used a pair of pliers and applied some 3-in-1 onto the valve shaft and managed to move it to the W position, so when HW is on, I only get HW through. However, when I connect it back to the valve, I can only move the lever as far as the mid-position so never all the way to H position. Obviously I can't change the valve lever through the actuator now.

Thanks in advance for any advice you are able to provide.

IW
May 2012