i know this isn't exactly what you wanted.. but...
I had the same issue to work through and just stopped by a local jewelry (diamond) store on an off hour. I asked them nicely (and offered the obvious no thanx as an acceptable response) if i could use their microscope to look at my stylus.
The not only were happy to let me do that, they were relatively curious and entertained by the whole exercise.
You may not be able to discern a slightly worn stylus, but you can certainly evaluate a heavily worn one, or one where the stylus has fallen off.
I had the same issue to work through and just stopped by a local jewelry (diamond) store on an off hour. I asked them nicely (and offered the obvious no thanx as an acceptable response) if i could use their microscope to look at my stylus.
The not only were happy to let me do that, they were relatively curious and entertained by the whole exercise.
You may not be able to discern a slightly worn stylus, but you can certainly evaluate a heavily worn one, or one where the stylus has fallen off.