I have been following this thread as well as the thread started by hansdejong
with interest, however response & guidance from the community has been scarce.
What I have done on my WTT arm is extend the cartridge to it is in maximum forward position and then focus on centering the cartridge alignment at the two null points on the protractor. I was not able to get the stylus all of the way out to the edge of the spindle circle. It did seem to take lots of time to get it right at the two null points. Once there, I locked down the cartridge headshell screws, rechecked the alignment and tracking force. Yep I had to repeat a couple of times because the !@#$ing thing moved on several attempts to torque-down the screws. I also needed to re-tweak the tracking force a little. I then set the azimuth, using 1kHz test tones from the Analogue Productions test LP
. and messed with VTA by ear until it sounded equivalent across the frequency sweeps on the same test LP. I'm not using any anti-skate. I don't have any other tools, except the VinylEngine protractor, tracking force gauge and a test record, but using this, I was able to get some spectacular results today. I'm pleased.
Bottom line, I don't think that the spindle to Pivot Distance is catastrophically critical.
In my case, the distance from the spindle to the front edge of the circle on the protractor is short by 4mm. I could rotate further, but it would be a LOT of work to move it off of the "factory" setting on the plinth. Again, I am now getting some really great balanced music and the imaging is fantastic.....so I'm calling it done-n-dusted.