Here are two pics of the engine. Another thig I wanted to add, I bought a muffler for a newer magnum .25 hoping it would be a direct fit.. no go, but I did bore it out and tap a new hole so it would fit. I noticed a small leak coming from the rear most screw.. I will go back and lap the surfaces to make sure they are flat, and use a better gasket... could this have been the root cause of my trouble?