[Mark Yacavone]

As Russ said, you can flush the oil out of one ,but most of the debris hides up under the weld seam at the radius high point. I doubt that will ever flush out.
If you don't have a drain plug (highly recommended) the best you can do is, first,
set the unit on the bench and slip a small vinyl hose through the hub and all the way down to the pilot area, and start a siphon going over the edge of the bench.
Once you get most of the oil out, then refill the converter with a mild solvent like mineral spirits.
If you have a trans input shaft laying around, you can then spin the turbine for a while to stir up the fluid. Siphon it out again , then blow it out with air until mostly dry.
That's about the best you can do , my friends.