The tonearm connector (Lemm) must be inserted into the junction box in order to get a correct VTF reading. Otherwise the unipivot arm will have external forces on it when you try to measure the VTF.
I suggest the following:
1. Have your turntable in the state like you are ready to play a record. If you twist the wire, whatever, then put a twist on it. I personally have no twist on my wire and have the Anti-Skate set to the absolute minimum. One donut at the top of the vertical bar, with the fishing line on the top, and no donuts on the horizontal bar.
2. Build up a platform on the side of the platter next to the tonearm. I actually use the box that the digital gauge came in and DVDs under the box to get the platform of the digital gauge EXACTLY the same height as a record on the platter.
3. Put a record on the platter, a flat one, make sure it is flat. Use the center record weight and put it on the box where the digital gauge is, in case you have to extend the platform out pretty far to the cartridge. The weight on the box, ensures you are not going to tip everything over.
4. Zero the gauge, line it up. When you put the cartridge over the platform, since there is a magnet in your cartridge, with the magnetic force you might see a negative weight. That is why it is important to turn on the gauge and zero it before putting the cartridge over the top of the platform.
5. Lower the cartridge with the stylus exactly in the center of the dot on the digital gauge.
6. do it more than once, which will kind of give you an average reading.
7. If your readings are off by a lot, then something is moving, or you don't have the stylus exactly in the center of the dot. Keep trying.
8. Move the whole setup off to the side when you are adjusting the weight, you don't want your stylus hitting the gauge.
9. Make sure you tonearm is not resting on the armrest when you are doing the weighing. Make sure it is not even touching the arm wrest.
10. Use the Allen wrench, and the back weight, which screws into the arm to fine tune the VTF.
11. To see the effect of height, after you everything dialed in, add a couple of more dvds under your platform and weigh it again, and you will see the VTF go up, probably by 0.3 grams or so.