What should be the weight of an 80 kPa pressure canner jiggler/pressure regulator valve?

I've recently bought a dial-gauge pressure canner here in China. It uses a steel jiggler/pressure regulator/counterweight which seems to be modern standard, having a 10mm hole in the bottom which sits upon the lipped metal steam-release tube atop the canner.

The problem is that, although the manufacturer's manual states that normal operating pressure is between 72-88 kPa, and the gauge itself accommodates that pressure and beyond, when using the canner the gauge only shows around 50-55 kPa at the point when the steam is heavy enough to put the jiggler in a continuous rattle (at which point it should mean that it's at normal operating pressure, as regulated by the included jiggler).

So, my first suspicion was that the gauge might be defective. However, if I apply light pressure on the top of the jiggler at the abovementioned moment, the gauge slowly begins to rise past 55 kPa, which suggests the gauge might be working right, then leading me to my second suspicion that the jiggler itself (which was the OEM that came with the canner) might actually be too light. There is no kPa marking on it, but one would expect it would be heavy enough to meet the specs of the manufacturer for normal operating pressure as per the manual. It weighs 78 grams.

So, I went ahead and bought another jiggler that was stamped as being an 80 kPa regulator (which, at just over 11 PSI, is safe for non-acid food canning at my elevation, which is really my main objective in the first place). Well, that new one came in at only 74 grams, even lighter than my OEM jiggler. Then, I read a negative buyer's review on Amazon about the exact same-looking "80 kPa" jigglers being sold from China, in packs of three, where only one of the three would reach 80 kPa (suggesting that some of these being sold were indeed underweight). So, I then ordered two different supposed 80 kPa jigglers of different types from other sources (one of which was "Supor" brand, which is a trusted name brand of cookware here) to check the weights of those to compare as well. Those both came in at 69.7 grams!

So, folks, my question here is how much is a standard 80 kPa jiggler really supposed to weigh?