my guess is that you ruined it. It's a lot cheaper to try to braze a sleeved joint made out of 4130 tubes.

You could yank the tubes, clean up the lugs, and buy new tubes. That's assuming you didn't fubar all of them

another thing you can do to practice is to get some brass and braze together random scraps of junk. I am always making myself new tools that are brazed together, there are plenty of examples on flickr