When I took it apart, I saw that one lobe had ben grinding against the case. So that was the previous owners mistake? About 0,5 to 1 mm had melted , but I got it cleaned up.Yeah the crank is free to move a little bit. But bolting the cylinder down creates a little bit of a load on the bearings and seems to hold the crank in place. You could also Loctite the crank to the inner races to hold them where you wanted. Make sure you put a bit of sealant all the way around the rubber on the seals and onto the case when you stick it all together