I use my TTS-100 for many things. I saw an improvement. I don't remember the source. I think it was on the Tormek TNT DVD.
My shop has fluorescent lighting. it's bright, but not good light. Sometimes it is difficult to see when both metal circles are touching the grindstone.
The improvement is drawing a single spoke on the metal wheels with a thin black marker. The thin black lines are quite obvious when they turn. When both wheels turn, the setting is correct. Clever and stone simple. it certainly impressed my little mind.
Ken