tracking force problem

I have a rega p9 tt with the rb1000 arm and rega ELYS 2 cartridge. The tt was set up by a rega dealer and the tracking force was set on the arm at the 1.75 g setting (recommeded for that cart). I recently bought a digital tracking force gauge and I had to adjust the arm to the 1.5 g level to get a 1. 75 reading on the digital reader. In short, is this normal....i expected minor tweaking only.....should i believe the digital gauge or the settings on the rega arm? Also, does this even matter is .25 g not even matter anyway?
Vertical Tracking Force (VTF) scales built into tonearms are notoriously inaccurate. The value should always be confirmed with a scale. Since few dealers are adept at setting up a vinyl rig these days, fine-tuning often falls on the user. Fortunately there are sites like this with many experienced members willing to help.

One thing those experienced users will tell you is that fine tuning a rig must eventually be done by ear. When it comes to VTF, all a scale can do is reliably get you to a reasonable starting point. It's now your ears' job to help you decide whether the optimal VTF is actually higher or lower. In general, VTF's too low result in lightweight bass, fizzy highs and audible mistracking - in that order. VTF's too high result in smothered highs and reduced microdynamics. It's safer to be slightly too high than slightly to low, since a mistracking stylus will permanently damage your vinyl.

A VTF change of .25g is quite large. I'm not familiar with the Elys, but most cartridges I've used have a sweet zone no wider than .10g, sometimes less. I'd suggest experimenting and learning what to listen for. The knowledge and practice you gain will serve you well.

How high/thick is the "weigh platform" on your new digital scale? Many of the cheaper scales now being sold as tracking force guages for turntables have very thick platforms which will not give an accurate read (the higher the platform, relative to a real record on the platter, the higher the reading will be, hence the need to reduce VTF on the arm to 1.5 to get a 1.75 gram reading on the scale). If the weigh platform is around 8 mm. to 1 cm. or more in height (quite common with a lot of these cheaper scales being marketed), it is quite possible that you could be getting readings with this kind of a discrepancy.
Try swinging the arm away from the platter temporarily. This allows you to create a separate platform next to the platter on which you can set the weighing machine at the same level as the platter.
I have a really cheap Haddaways (e-bay seller) electronic weighing machine which is accurate. I figured it was easier to do the above than changing the VTA by the height of the machine (something Fremer forgets to do on his DVD!).
I worked this out on my own so please, if anyone sees that this might not be accurate or have a better method, I'm open to feedback!