I went to replace my proofmeter cable but am puzzled by what I found. I pulled out the old broken cable end and it had the part in the photo below attached to it. One end has a square hole and had a short piece sticking out, the other round with the broken cable end in it. I can't figure out how it goes back together. Is the square piece supposed to be separate? The new cable doesn't want to go all of the way through and doesn't stick out far enough anyways. Can anyone help?