Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I am working on this model steam engine I picked up a while ago. Today was the first time I actually tried to run it on steam after successfully running it on air a while ago.  I had expected there would be a valve to open in order to pump more water into the boiler, but the fitting going into the boiler did not have one so then I thought that maybe it was a one way flow valve so I pumped the water to the 3/4 way up the sight glass and fired it up. As the water heated there was some slight leakage at green fittings around the sight glass and a couple other fittings.  I left the sight glass alone, tightened a couple of the fittings but before I got enough pressure to run the engine I noticed that the handle on the boiler pump had pushed back and there was nothing preventing the boiler pressure from back feeding the pump.  I am suspecting that I need to take the valve apart and clean it.  I am attaching 3 pictures, one of the boiler feed valve, one of the pump and one of the engine.  Thank you for any help or thoughts on this.

Thank you for the response.  I took it apart and There is a small steel ball and it seems quite dirty so I am going to clean it up and get a small brush to clean the valve out.