Stylus force digital scales

John_tracy is absolutely correct, once the weight of the cartridge is supported by the measuring platform the magnetic force is neutralised, as he says "think about it".
For me the most crucial issue is that the height of the measuring platform is exactly the same as the height that the surface of the record would be. Even small differences less than 1 mm can influence the force by >0.1 gram. This obviously depends on where the the centre of gravity of the tonearm is, these numbers refer to the Kuzma 4 point. I suspect that people who change the tonearm height for different thickness records, are actually hearing the change in tracking force, rather than VTA/SRA, since such small adjustments make hardly any difference to VTA/SRA but make a huge difference to tracking force.
I have found the Ortofon DS-3 (only available in Japan) to have a measuring platform, close to the thickness of an lp. The Clearaudio is much too high as are most of the others, including the el cheepose.

Dougdeacon, thanks that is something I have not thought about. I have confirmed on my el cheapo digital force gauge that it does measure the correct weight despite the attractive force by zeroing with the cartridge on the platform, and then lifting the cartridge away, and it gives the exact negative reading of the force I set in the first place. The magnets on my Lyra are unbelievably strong and I'm sure the force on the suspension during measurement is not good for the suspension...finally a reason to never measure with a gauge that is magnetic, and a compelling one!!