Eddy is right but he forgot to mention all the details; it’s true that an electrolyte can cause what we see on the blocks, but what he forgot to mention, is the nickel have to be in close contact with copper in this electrolyte, and the only way it can happen it’s when defective platting expose the copper, that explain why other manufacturers don’t have the same problem , now Ek will replace the block, of course they was damage before been put in the electrolyte, and EK ask you to not use anymore electrolyte to not damage other block with imperfection. All that to cover manufacturer imperfections. .