Just trying to make my job a bit eaier here because it's cold and wet outside but what do you make of those cans of stuff called Gunk, you put it in the engine when warm, run for a few mins then drop the oil. It supposed to break up the slude in the engine and clean it up, I wonder if that might break the pieces up just enough to come out of the sump plug hole?
maybe pour some oil through once the plug is removed to try and push some bits out.... second thoughts looking at the haynes, it's only a few bolts so should be relatively easy and quick job to do whilst I'm changing the oil.
Tim