Nine and stuck. I wonder if I haven't already made a mistake.
Boy, I sure don't get Easy on this one.
Finally. Found the difficult loner.
Did it! No green. Let me introduce a new term. "Loner-n," where "n" is the least number of empty cells in one of the cell's three constituencies -- row, column, block. Loner-3 is easy. Loner-4, common and quite manageable. Loner-5 is difficult, such as today's. Loner-6 is possible, but I don't think I've ever seen one.