[BrianG]

I just read this thread, and am wondering if the problem is simply the method of soldering. You said the solder doesn't "stick". If you are using the right solder, the only problems I can think of is that 1) you are trying to heat the solder and drop it on the connection, or 2) there is a varnish layer on whatever you are soldering, or 3) you don't have enough heat for the job, or 4) your tip is heavily oxidized.

When soldering, you have to heat the items being soldered and let the solder flow into the connection.

If there is a varnish layer, the solder will not stick to it. Use an Exacto knife and scrape off the layer until you get to the bare metals.

It sounds like you have a decent iron - at least decent enough to do the job. I use a 40W Weller and it works fine, but it's a little small for soldering heavy gauge wire or other jobs where there is a lot of metal to solder. Heavy wires/traces/connectors act like heat sinks so you need a thicker tip so it doesn't shed it's heat as fast.

As you use your iron, the tip will get oxidized and turn black. You should have a damp sponge handy to wipe the tip off. You have to keep it clean or you won't have good heat transfer. You can use flux to help with this.

Also, when you get a new iron or tip, you should burn-in the tip. This is a process where you just heat it up and put solder on the end and let it coat the tip. Wipe it on the sponge every so often and re-tin.