Ive loaded the basin with zinc and copper ingots and fueled the blaze burner but the arm on the mixer will not extend, ive put dye in to see if by some chance it wasent working properly but, it worked with dye is there a new recipe to make brass

If you check the recipes for brass ingots you will notice none of them use the mixer. You need to use the melter from Tinker's Construct to melt down Copper and Zinc then combine them in the mixer.