You need to go back to Color 3 and if it's the center block you are referring to...you need 1 2 5/8" sq.... when you take 1/4" seam around it that leaves you with 2 1/8" center block. Is this what you are referring to as the center block?
Did anyone else have problems, all mine fit together and in the original directions it tells you one 2 58" sq!
Hope this helps.
Hugs,
Cajun