I need some guidance on how to remove this late 1980's vintage track light mounting strap or hanger (brace?) from the 4" round junction box? It appears to have the two small threaded rods, that the cover plate attached to, go all the way up through the two layers of the metal hanger. There are also two philips head screws holding the "top" of the strap into the j-box just above the lower metal strap. Both appear to be going into some of the plastic 'tabs' of the j-box.
If you can push the machine screws up, then you can just spin the bottom half of the bracket and get at the screws that are holding it.
If you can't push them up, grab them with locking pliers (ie, visegrips) and spin them out.
If that doesn't work, use brute force to bend the bottom half of the bracket to give you access to the screws holding the top half. Then you'll be in a better position to assess the hanging machine screws.
oh, and so I can sleep well at night, please put a cap on that black wire... you never know who'll flip a switch on you at the wrong time...