Older Drayton Y plan with new Boiler. No hot water. How to remove actuator?

Elderly Blind relative had his working Vulcan boiler replaced with a Vokera pressurised boiler and a room Stat was added.
Rest of the system was left intact with some very old Drayton hardware a TA/M4 3 Port Valve with an RB2 Relay wired to a Potterton Ep2002 5/2 Day Electronic Programmer. Can find ZERO documentation on the Relay and Valve hardware and no wiring diagrams as the wire are non standard colors.

A few extra radiators were turned on for the cold weather & the hot water has now stopped working. (suspect the sytem was not flushed properly when the new boiler was installed ?)
CH is fine as long as the Hot water thermostat is set to above ambient and calling for heat. It was never quite right after new boiler install in that if the Thermostat on the tank called for hot water the central heating would come on.
Now the boiler doesn't fire at all for the CH unless the thermostat on the tank is turned up even though there is NO Hot water.

Trying to remove the Actuator on the TA/M4 Valve to verify if that is part of the problem. But no idea how to remove and don't want to force things. There is no button to press like on more recent units???? Any ideas ??
Would like to put it in the mid position by hand if possible so at least he has hot water till we sort out a proper fix.

The wiring seems to need work. Have enclosed the inside of the RB2 Relay box if anyone has any insight. 10 year old posting here said "TA/M4 I think used a heating off and not a water off" ???

If the Valve needs to be replaced what would be a better direct replacement that would fit without redoing the piping ??

Thanks.

 

You have a Flowshare.

https://www.google.co.uk/search?sxs...=2ahUKEwid0IDuy5jsAhXLQUEAHf-ZA-oQ7Al6BAgDEF4

There are two square nuts that appear to be washers holding actuator.

 

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