.This is an old one. The new ones are pretty fragile junk.
In the second picture you can see a thick paper insulator on the right, should be one on the left too, must have fallen out in the drawer. You can also see a thick insulator under that wedge shaped stud.
When you hook your battery cable to that stud the stud can not be allowed to turn when tightened or it will go to ground through the insulator. I've screwed them up too when tightening up the nut on the cable.
