I don't know if this will help in installing the magnet, but I am going to paste some installation instructions that someone sent me back when I was confused with a 10BP4 which came with a single field. I had obtained a double even though the single worked fine. I figured that there had to be a reason for such a specification or they would never have made the darned things. I still don't know for sure what is 100% correct, but anyway here is what he said:
The clamp with black tubing should face the base of the tube. The flat plate of the trap should be on the side of the neck opposite the side of the tube where the HV anode connection is located. The trap should be about halfway between the back of the focus coil and the tube base. The clamp should be just snug enough to hold it stable and prevent the trap from sliding around the neck under its own weight but loose enough to allow it to be moved around by hand to find the position giving brightest raster and eliminating neck shadow. Once properly positioned, secure the clamp so that the set can be moved around without disturbing the ion trap setting by vibration. The clamp should grip the neck securely without squeezing. Above all, don't over-tighten it.
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"