You have my sympathy as I have just encountered the same problem joining this type of block with an Ohio Star. It has been an absolute disaster. I have tried clipping and fanning out the seams, but it makes for a very untidy appearance and there are still bumps. I looked on You Tube, I think it was a Fons and Porter tutorial, which suggests pressing the seams open. It also defines the X much better than pressing to one side. I am going to try this with diamond blocks, and a prayer! By the way, I still think you have a done a magnificent job on your blocks, I wish mine looked half as good.