Jaguar Boiler, heating dying slowly

[goldenhoneyhive]

Hi,
Have a Jaguar28 boiler been running for something like 7 years very satisfactorily.
Heating has now developed a fault, it is gradually closing down, only radiators nearest the boiler are heating up, the others are colder the further they are away.
Everything else is OK. the DHW is fine and the boiler fires up for heating correctly, the pump appears to be running.
Is this a pump failing?, it happened too suddenly for a blockage, I would have thought.
Any help would be much appreciated.
How easy is it to change the pump / valves, I am a retired Hydraulic Engineer, but have physical hand problems.
Regards H

 

[compheat]

what make of pump is it with most pumps you can just change the head/motor.its not a difficult job for some one with your qualifacations

 

[Agile]

Have you checked that the diverter valve is returning to the CH position after DHW use?

If it was a flow related problem such as a pump the the flow would be hot and the return cool!

Tony