The problem with the 'B-A' button on these 9083's, is that they used to get some real hammer in the field. Not for what you might think though, as in testing the B leg to Earth, then pressing it to test the A leg to Earth ...... etc etc. This requires just a gentle press of the button.
However, for a rough guess as to the distance a pair of wires is travelling, we would set the scale to the 'Ohms x 100' scale and rapidly press the 'B-A' button. The ammount of scale deflection of the needle, would give an approximation of the distance. It saved on getting the 'Mole' out.
But you may have already thought of that as well.