I have a British Gas npc 555312 mid position actuator code BGMVSP-23 which looks the same as the Drayton motorised control head in this video. My central heating wasn’t working on heating only. Central heating only with hot water. These 3 port valves do default to hot water. By removing the motorised control head I was able to move the 3 port valve spindle about eighth of a turn only with a small adjustable spanner. I then put a flat driver in the spindle orifice in the motorised control head. Turning the programmer on the workings on the motorised control head started working. There’s a few videos on RU-vid about checking central heating controls wiring and replacing thermostats and three port valves. But I’d suggest checking you don’t have a stuck valve first.
I've the same problem with my Myson power extra motorised valve for the downstairs heating... I find it only comes on after I tap it.. I don't know whether to buy a new one or try fixing it...
