Get into the attic and set up your chandelier lift. It is the way to go. You'll have a customer for life.
They used to have to lower chandeliers to replace the candles and dust/polish the unit. So you can do this just as well today. Get into the attic and cut around the box after tying it to the joist using an eyelet and a rope. Slowly lower the fixture to the ground. Now set up your box to tie the box on the new fixture to. Or go with a general use Recep and set it up cord and plug. Go downstairs and set up your replacement chandelier, tie it to your line, and pull it up until the scussion plate is flush. Now secure it in place. Wire or plug into your new box. Done. No need for scaffolding.
Keep in mind, get into the attic. The existing chandelier might actually be set up this way. If it was nicely installed you'd never know without getting in the attic.
Let me know how it goes.
You can MacGyver it, or you can set up scaffolding.
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