Note about leaning out due to leaky tank makes sense. It will be my lesson to check tanks better. I remember that when I was learning how to fly, my instructor told me to always check the tank for leaks. I know that I did that when I build this plane, but it was about two years ago and it looks like the rubber has deteriorated some. I also remember one of the guys at our field tell me to check the tank, and I was to lazy to take tank out of the plane so I just squeezed the exhaust line shut, and blew air into the fuel line. I thought that I could reach a pressure at which I could not blow any more air into the tank.

Well, next time I will take the tank and put it under water and test it properly.

I have pulled on the head a little harder and the sleeve pulled out of the case. Piston ring is looks like it has a missing section about (30 degrees around). In the best case scenario, what parts would I have to replace? Piston ring, sleeve, anything else?