I agree the 10x lens is required for the final alignment so you can visualize the lines in the mirror as well as the cantilever and ensure you have it correct. I like to use the 3x lens when I am adjusting overhang as it will allow focus with enough magnification from a little greater distance than the 10x, avoiding the finger lift, when viewing the stylus from the side.
cartridge alignment
When I look through the illuminated magnifying glass provided by mintlp if I do not have the magnifying glass set up correctly, it can appear as if the cantilever is aligned but it is not due to distortion from the lense of the magnifying glass not being in the correct position with respect to the cantilever. How do others make sure they they have their magnifying glass set perfectly while aligning their cartridges?