I have an old-style, convector-type, wall mounted room heater that has a
small leak. It is similar to baseboard heat, but the heat is provided by
the hot water that goes through the convector element.

Here are some photos:
http://i44.tinypic.com/2a7izh0.jpg

http://i40.tinypic.com/v79r9y.jpg

http://i39.tinypic.com/28c3pk7.jpg

http://i40.tinypic.com/oa6wbc.jpg



The convector element has a very tiny leak near one end that I can't quite
locate with the convector connected up and working; and, even with it
disconnected I can't quite locate the pinhole or whatever that is causing
the tiny leak.


Buying a new replacement convector is not really an option since almost no
one makes or sells them. I could replace the unit with a regular (used)
cast iron radiator that I can get locally, and probably get a regular
radiator cover for it.

But, before doing that, I tried cleaning off the whole area with emery cloth
and solder flux with heat, and then tried heating it with a MAPP gas torch
and soldering the whole area. I don't know if the element is all copper or
some kind of copper/brass combination, but the solder didn't really seem to
want to adhere to the metal very well. So, I tried just spreading around
hot melted solder wherever I could. The result was that the leak is now
barely detectable, but it still drips a tiny bit.

My question is, is there some type of soldering or brazing technique that I
could try to see if I could seal the tiny leak?