Power cable connection issue, plug slightly sags and disconnects

That's fine.  Or you can do one wrap with teflon tape and cut a small block of pink foam  to place under it.

Is it disconnecting from the wall, a power conditioner, or from the back of  components? I haven't had any heavy cords disconnect from the back of components. for wall duplezes and power conditioners, it is possible to get ones that have a really tight fit, like those from Furutech or Synergistic Research. Typical household-grade duplexes are very cheap and not built for grip, and aftermarket ones do a better job and improve the sound quality. 

It’s a $700 10 gauge power cord connected to the back of a component on the rack.

I guess I can find a way to prop it up but that’s problematic and may not be workable. I think it was doing an OK job when it was connected.

And now I’m finding it’s not connecting at all when I jostle it around. The component prongs sticking out are very secure not the problem.

Sounds like its the power cable’s connectors that are the problem. Better connectors also have a tighter grip. Which cable is it, if you don’t mind me asking?

This was covered not that long ago in another thread.  Solutions: wrapping various kinds of tape around the connector, suspending the cable with various kinds of thread or line, propping up the cable with various home-made contraptions--I remember one which was a cradle made out of Lego bricks.  It's a fact of life that there will slight variations in the standard: I've experienced both connectors that it was virtually impossible to get into the socket, and connectors that were loose.  The weight of many high-end PCs doesn't help!