Bigalt -
In your methodology for levelling the arm the stylus has friction or resistance imparted even by the smooth record. A better way to check the level of the bearing tube (and the efficacy of the lead out wires ) is to add enough mass or move the counterweight to zero the tracking force. That way you can check that the arm is not running away in one direction, and if you tap gently you can double check the resulting movement is equal in both directions. Or buy an accurate digital level, you don't need an audiophile one ( usually overpriced ) buy an engineers digital level from an engineering supplier.
In your methodology for levelling the arm the stylus has friction or resistance imparted even by the smooth record. A better way to check the level of the bearing tube (and the efficacy of the lead out wires ) is to add enough mass or move the counterweight to zero the tracking force. That way you can check that the arm is not running away in one direction, and if you tap gently you can double check the resulting movement is equal in both directions. Or buy an accurate digital level, you don't need an audiophile one ( usually overpriced ) buy an engineers digital level from an engineering supplier.