I must defend myself, this is my first dry frame rebuild and pre-1970 to boot. Nowhere in the workshop manual, Section B1, is the breather tube mentioned. I did't attach the breather tube to the spigot coming out of the primary case BEFORE installing the engine in the frame. This created a new challenge that can easily be avoided, which is why I'm posting this! I had to lay the bike down on a foam bedding I've had around for camping. I used Air Line tubing intended for big" over the road" trucks as replacement for the crusty tubing that came off the bike. The I.D. fits well and the O.D. is not too large so it won't interfere with the chain and get eaten away. Not only is it thin wall tubing that is rigid so as not to collapse, it can be heated with a heat gun so that it slides over the fitting easily and then cools back down for a very snug fit. It cost me $1.60 a foot at my local parts store. Again, credit goes to folks like StuartMac and the search feature of this forum. StuartMac warned of this very thing happening to the unsuspecting types like me and also said be aware that the tubing must be thin wall to avoid the drive sprocket. The air line tubing was suggested by an experienced counterman at the parts store. This is another advantage of living in small rural towns in farm country. Lots of big equipment operating around here and farmers tend to fix everything they possibly can by themselves....