Hello together I have already searched the net, but I have never found a real solution for the known problem. Therefore I would like to describe here my solution approach: I have a Hercules Optima with plugged manifold connection. With this connection a steel tube is poured in in the aluminium cylinder, which likes to loosen, so that the exhaust is unpleasantly loud and the whole oil soap runs down at the manifold. The idea is now to mill out the tube. Before welding, of course, the spot has to be irradiated so that there are no problems with welding. I have now tested my procedure on a Prima Mofa cylinder before I go to my rare Optima cylinder. Here you can see how far I am at the moment. The steel tube at the bottom of the cylinder has only 2 holes, which are poured with the aluminium of the cylinder. If you mill the aluminium there, you can start the tube. I had to grind the cooling ribs around the outlet a little bit away in order to be able to weld properly later on. Since the cylinder has a grey cast iron socket, I am not worried about delay in welding. More pictures will follow