Yes, the mini butane torches that come in soldering kits.
you might be best off getting some good 4ga wire and 8ga wire and making your own fusible link.
I do not have a fusible link on my car, it’s a 4ga solid wire from the fuse box to the alternator.
What I meant was the fuse itself isn’t the cause, like the initial issue the blown fuse caused a voltage drop to certain fuses in the interior fuse box. In this case the fuses in the engine bay have continuity meaning the cause of the low voltage should theoretically be the wires between the battery and the fuse box.testing for continuity just means your testing if the fuse is still good and there is a connection that continues through them. More than likely if you fix this it will fix your other electrical problems. 7.6v is right below the threshold of almost kind of sorta working and just enough to give 12v electronics fits.
Maybe .5-1” I agree from looking at pictures it appears loose, trying to figure out how to hold the shaft in place so I can tighten the nut down without it spinning.How much movement are we talking about? From what I remember when I did my rears, that doesn't quite look tight enough. I seem to remember that when I did mine, the black rubber bushing or whatever was squeezing out a little from under the big washer/cap.
Before you try to tighten it, take the nut off to make sure you have threads to tighten. If you don't and continue to try and tighten it, you may find there isn't any more threads. Why not take it off completely, and/or, check for a part number to be sure they're correct? Might save some headaches.