I'm nearing what I thought was the final stage of getting a 2000 Pegaso back on the road.The bike had been sitting for a long time and the petcock was so hard to turn I had to use pliers. I got a NOS petcock today, and I can't turn this one at all, even with pliers. I filled it with silicone spray and let it sit for a while--no good. So I pulled it apart and this is what I see. With the knob, faceplate, and wave washer off, I can see the valve, but I can't get it out. It's not held in with a circlip or anything else I can see. Ordinarily I'd expect it to slide out of the petcock body. Suggestions, please, for freeing it up.