The proper way to fix that is to cut the exposed wire off, restrip it, then use ferrules.

https://www.arrow.com/en/research-and-events/articles/what-are-ferrules-and-why-should-you-use-them

No solder, solder is junk. Clean copper, crimped ferrule ends, then put into the screw connectors.


Or, get rid of the screw connector and use something modern to connect the wires.

LOL.
To paraphrase a Porsche engineer who spoke at a PCA event back in the 60s, “If Porsche had vanted dees ‘ferules’ on zee cars, Porsche vould haf put ferules on zee cars.”

I haven't used a gun like the one in the OP in years. I used a style similar to the one in the video Baz posted. For some reason, they just seem to work better for me. My method is to let it heat up, dip the wires in flux, put a ball of solder on the iron, touch it to the wires that are connected together (or individual if just tinning) and wait. Seems to work well for me. Can't say it's the right way or the best way but it works.

Funny confession? After dogging out the Weller (I have two!) for the pencil type. I now read up on cranking down the connections.

I was (unsuccessfully) using mine a week ago to heat up some crappy dirtbike plastics. I suspect a touch of maintenance and I will be good to go.

The right tool for the right job! As we have all seen, PPOT is a wealth of knowledge!

The machines that built the car were full of ferrules, because they are the right tool for the job. My car has ferrules where there are bare wires going into screw terminals. Why would you not just do it right, do it once, and never think about it again?

I'm not as familiar with mid-1950s German machine tools as you apparently are. I wonder - why they would build the tools with one technique and build the cars with another?

I'm happy for your car. My car doesn't have them, and never did. There are dozens of tinned screw connections in the car that have worked fine for 69 years and are still working. The only connections that I have to fix are the ones where some bonehead cut the wire and jammed it back into the junction block without tinning the wires.

For one thing, there is barely enough space in the junction block to get the wire into it. It is so tight on the 14 gauge wire that after tinning it I had to file it down until the copper was showing to get it into the connector. Adding a ferrule would have made it impossible to fit into the junction block.

It's an old car built with old technology, which is why I own it. If I want a new car, I know where to find one - with ferrules.