Shure Stylus Gauge


As some of you may know I have had some questons about the use of the Shure SFG-2 Gauge. Well at the risk of being extremely annoying here is one more:

I have noticed that when I place the Gauge on a record instead of the platter mat, the VTF reading on the gauge is much more higher. (ie. on the mat the reading is 1.5 grams, on the record the reading is 2.5 grams, then if I place it on the platter without the mat the reading is much lower roughly around 1 gram). The Shure instructions read "for better stability, place the gauge on a record" when I do this it seems to balance okay, then if I push the lever down (stylus still on lever groove) the tonearm and lever stay down and won't balance back up. It just lies against the record. Weird since it balanced before I pushed the lever. Could there be something wrong with my RB300 arm, I just had it rewired and VTF spring removed, or the guage itself?

Thanks,
Frustrated.
mrcs99e0
My theory would be that there is something causing mechanical resistance at the arm bearing as the headshell goes lower. This would explain both the different readings with and without an LP, and also the fact that the arm stays down when pushed down.

There could be a few reasons for this:

First, is your arm mounted at the right height at the pivot? The bearing will only allow the arm to swing free within a certain range.

Second, does your arm have two separate balancing mechanisms, ie, a gross mechanism to get the arm to balance (0 weight) and a second calibrated one to set the actual weight? If so, you should always calibrate the the arm to zero before using your scale. If not, the arm may not be within a range in which the counterweight and stylus force are linear with respect to eachother.

Third, is the tonearm lift interfering?

Fourth, there is some friction at the pivot of the scale (good news) or some friction at the tonearm bearing (bad news).

Hope this helps.
How can I tell if it is the arm bearing. Is there a test I can do? When I set the counter weight to float the arm, it seems to float, and bob up and down, side to side without hesitation at all.
the bearings might do ok but the pivoting position plays the vast role in this situation. the cartridge weight oght to be the same whether you place mat record or none of these. certainly the readings on the soft mat might not be pricese anywhay.