Yes, indeed it has always been that way. The problem is that with the 15 cm radius aperture it's very hard to reach inside the magnet and weld the probe holder in place. Gluing didn't work well at all. The welder being right handed had an easier time reaching into one than the other. The only instruction I gave was to get it in as far as you could, which was still in the fringe field region and very sensitive to position. The purpose of the Hall probes in the quads in general is to simply give a relative measure of the fields. None of them are intended or ever were intended to give an absolute measure.