It is now obvious why the engine failed. The flywheel damper plate and adisintegrated. Pieces of the spring/rollers were cut through and jammed against the housing and another loose piece next to the damper plate. Note one piece of spring embedded in the transmission housing.
In the photo above you can also see several of the swings have stopped rotating and have been ground flat. At the 3:00 position you can see a piece of spring missing and at every position you can see groves cut into the spring, ready to release more pieces. The plate itself had been worn, allowing the springs to move back and forth and not simply spin. The photo below shows the flywheel grooved by the piece of spring jammed in the housing, which is what caused the engine to seize.
