What do you do when you realize one of your employees is a poor culture fit when you're a small startup and every employee feels so integral?
You should talk to the individual and try to find out what's creating a poor fit. On another note, cultural fit is often discriminatory in practical scenario. Hence, I would like to know what's your definition of "Culture" and "Culture Fit" before advising anything further. Perception in such cases could easily get driven by stereotypes.
Would, also like to see your sanity checklist. Hope above helps!!