Back Boiler pump

[owington]

Hi,
Been to a job today with gravity hot water and pumped central heating. When the heating is switched on the pump runs for 5 minutes or so then stops. I have removed the vent screw to check its actually running. I thought there may be a problem with the programmer so i have disconnected the wiring to the pump, turned all controls off and ran the pump on a seperate 3amp plug straight to a socket. It seemed to run ok for a while but after switching it off at the socket it refused to start again. After 5 minutes or so it would start up and the cycle continued. Is there anything that can be done to fix the pump or does it need replacing?
Thanks

 

[dancinplumba]

it is tired and needs replacing imo

 

[Mike Jackson]

Replacement time.

 

[Puddle]

Just replace it,if you attempted repair,you can not guarantee reliability and end up replacing anyway,maybe in unchangeable time

 

[owington]

Thanks lads, will replace pump.