Does he work for a company and this is a private cash install in which case he may not be registered in his own name and not able to register appliances.
If you add your location you may find someone on this site close to you that knows this boiler.
It's very unlikely to be the gas valve so you need to get the other part checked first which I would check on a service.
The pump should be connected to the pipe on the side of the Warwick fitting.
The top fitting should have a rise on it and be connected to the vent pipe.