While regenerating old damaged cylinders you can encounter many surprises. The stub did not stand the pressure and failed. This called for a hand made stub which will probably outlive the cylinder.
In addition to the stub, the cylinder received a new cast iron sleeve. The cast iron sleeve was made in house from raw material. It is very important that the cylinder windows are perfectly matched. They have to have the right angles and sizes to match the factory standards so that the power output is the same as in a brand new engine. The below pictures present the cylinder before the final boring so that the window matching can be better observed.