I am not a plumber, but I soldered a T-tting into a ½" copper pipe, using a propane torch. I used flux (which was 10 years old, does it expire?) but unfortunately, it has a slight leak because apparently not enough solder got into one of the joints. Then I tried to touch up by adding more solder, but it ended up just getting a glob of solder on top without fixing the leak. Is there a way for me to get the solder in there to stop the leak, without replacing the T-fitting?