Hi,  I'm surprised that nobody has mentioned using "Tix Solder" for
this job.  Tix is a very strong solder (4000+ psi) that melts at about
275 degrees F., much lower temperature than ordinary solder.

Tix iridium solder was invented in the 1940s by a fellow who was making
jewelry.  He wanted to add some details to a piece of jewelry that had
been soldered together without accidentally unsoldering the previously
soldered assembly.  Although there were solders having various melting
temperatures available for sequential assembly at the time, he didn't
always know which solder had been used on a particular piece.  He found
that iridium solder melted at so low a temperature that it was always
safe to use.

He made the solder in a small lab in Montana with the help of family
and friends.  A school girl friend of his daughter (I think) was hired
part time to help with packaging and decorating some other items he
sold.  Over the years, she took on various other jobs in the business.
She alone is the surviving member of the group and she actually
produces the entire world's supply of Tix herself.

I had a nice chat with her a couple years ago.  It was soon clear that
she was not only the office manager, but the shipping clerk, and the
metallurgist and the production manager and the production department.
She does have a part time book keeper.  She got my order out very
quickly.  When I called back two hours later to order a bottle of flux,
she had already taken the first box to the post office and had to send
a second package.

It's probably easier (for you and her) to buy Tix from someone on
eBay or a clock supply house like www.merritts.com   Model builders
and jewelry makers also sell it.

This stuff works wonders and is simple to use.  I don't even bother
getting out the soldering iron or torch any more.  A couple years ago
I needed to join the nine large pieces of a crankshaft for a barrel
organ (1/2-inch brass, etc.).  I pressed the parts together in the
correct shape, applied a little Tix flux, and laid them on the bench.
Then I got out the heat gun and warmed them up for a couple minutes.
Just a touch at each joint with a piece of Tix solder and the parts
were bonded.  (I'll send a picture for the Archive.)

The great thing is that there is no burning or even discoloration
of the part (like you get with a torch).  And, of course, there is
no distortion or de-tempering.  Lastly, it is _much_ stronger than
regular solder.

By the way, on the tracker bar, I would heat the whole thing up
a bit with a heat gun, but not up to soldering temperature.  Then use
a soldering gun to heat the joint locally and apply the solder.  Just
tap the tube back into place and use the Tix to solder the old solder
back together.  Good luck.

Craig Smith
near Rochester, New York, USA

 [ Thanks, Craig, I'll put the picture at the MMD Pictures site,
 [ http://mmd.foxtail.com/Archives/  -- Robbie