Doug Fattic 

Now that I see a picture of how close the break is to your lug, I'll recommend a different but unfortunately a more expensive approach. It is possible to splice in a new section of tube using a section or sections of tubing with a wall thickness of 0.058". This is the same thickness of tubing that might have been used on an outside sleeve but of course with a smaller OD. Here are some pictures of a repair I made of my personal bike that came off the roof of my car while going down the highway. I used my lathe to turn down short pieces of tube that would just slide into the inside of what was left of my original top tube and the section of new tube. It took 4 brazing sequences to do the job (sleeve to one end of the frame, sleeve to one end of the new TT section, sleeve to the other frame end and finally sleeve to new section) before I could repaint it almost as good as new. These pictures unfortunately don't show the lathe turned sleeves so you will just have to imagine them.


The damaged section of my top tube cut out

Preparation to braze in a short stub of a tube into what is left of the top tube by the seat lug.What looks like a new top tube is really just an old tube used to hold the stub and not the final tube. It keeps the stub in the correct position.

the seat tube side of the top tube has been brazed in and filed. The head tube side has been brazed but not filed yet.

the completed frame with a new section of top tube after I have repainted it

Of course all this work comes at a cost and you will have to figure out if the price of the repair is worth it to you. it always will be if the frame has sentimental value. It is sometimes possible to find a used one that costs less. It is possible your local framebuilder might find it easier just to replace the tube. That might involve replacing the lug as well. I like splicing in a new section preserving and not disturbing as much as possible what is left of your frame.