mijostyn
... But out of level a tonearm will add additional skating forces ...That’s true.
... in an ideal world all parts of the turntable should operate in exactly the same plane.Yes, or at least in parallel planes for the turntable, plinth, and arm.
It is just a good measure to put the bubble next to the part that matters the most ...If you’re using a typical little bubble level to set up your turntable, it’s no wonder that you have some of the playback problems you report. You’ll get more precise results with something like this.
... Unless you are using an arm that is dead straight raising and lowering the arm will change the azimuth ...Correct. But there’s no reason to accept a turntable setup where those critical component parts - turntable, plinth, armboard/pickup arm - are not in proper alignment. If they cannot be properly aligned, then one or more of the parts are defective. Or poor quality. You've previously said that your stylus tilts towards the spindle when the arm is raised, but I wouldn't accept that from my turntable setup.