If you guys would quit your cushy jobs and start driving a semi, you'd know what to do when you hook up to ANY 5'er! LOL
Here's what I do:
Ensure the trailer wheels are chocked at least in the front, preferably front and back.
Ensure the kingpin jaws are lubricated. I use a spray grease that Mystic sells.
Back up to the kingpin until the jaws lock.
Get out and raise the landing gear just enough to get them off the ground so you don't bend them.
Check that the jaws are closed by visual inspection with a flashlight.
Plug in the pigtail.
Get back in, put the truck in drive, engage the trailer brakes manually, and tug against the jaws.
If the jaws are going to malfunction, this is when they'll do it.