Audio Additives Stylus Force Gauge inconstantcy

I recently purchased an Audio Additives Stylus Force Gauge and it is driving me nuts. I get inconstant readings every time I lower the stylus onto the little black dot on the plate. Without moving the arm, every time I lower, raise, lower, etc., I get a different reading between 1.68 - 1.88. The batteries are new, device reads 0.000g at start up, calibration checks out using supplied weight, room temperature is 72F, no interference from tonearm lifter and everything is level.
Anyone else have this problem?
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I still use the old Technics that came with the EPA-100 arm. It's electronic but analog, not digital, and doesn't give you milligrams (which are SO important). It's just a needle that swings from .5g to 3g, with markings for each .1g — and I can squeeze the needle between them for .05g. Accurate enough for me, and utterly consistent. Not high tech, but cool in a retro way. 
That is a very big discrepancy; it’s normal to have some minor discrepancy with any of these gauges and especially those that have 3 decimal point resolution but that is huge. Also, try to hit the centre of the dot each time.

In light of the fact that scale takes triple A batteries, I would replace the batteries first to see if that might fix the problem if you are using those that came with the scale. You may already have some extras around; if that doesn’t correct things then, yes, look for a new scale.

The body of the Riverstone gauge---they actually make two, but get the one with the extension arm which puts the stylus at playing height when measuring VTF---is made of a tough plastic, and that extension arm of a non-ferromagnetic grade of stainless steel. The gauge has resolution to 0.005g (!), and can be recalibrated to zero via the 5 and 20 gram weights included. Riverstone Audio has a video on You Tube in which the gauge is displayed, described, and explained, and then demonstrated.

The ubiquitous electronic gauge that most companies are rebranding and marketing as their own is, in comparison, a piece of junk, regardless of price. Many of them sell for more than the Riverstone, some much more. I mean come on, $28.95---whaddaya got ta lose?! For more details, see the Riverstone Audio website. 

Did you set the anti skate at 0 before you did the calibration?
Here ya go!
Another possibility is that it’s telling the truth, as in bearing issues with the arm.

No mention made of the type of tone arm.  If a unipivot that possibility is out.