How much magnification required to see stylus?

You can get inner groove distortion from a dirty stylus. You can check for gunk buildup on a stylus with an 8x loupe. I do and it works.

Then I clean the stylus with a Magic Eraser, brush away the residue, use the loupe to ensure that the stylus is clean and play the cartridge again. If the distortion goes away it was a dirty stylus. If the distortion remains and your alignment is good, it's probably time for another stylus.