Normally, I would resort to the seam ripper and remove the weak triangle and insert one of a stronger color. But. sometimes I'm lazy. I certainly didn't want to deal with the "right way" this time. The lost triangle was one of the two first to be sewn in the sequence, which meant the whole block would have to be torn apart.
Then I placed paper towel over the triangles and pressed it with a hot iron. The wax is absorbed by the towel and the color is left on the fabric.
Ahh. Much better, This is not my favorite block in the series, but it will work.