My problem is that the vertical throw of the drivers seat is only about 4" and I need to double that. My 2013 Prius Two, not II as it is not a 2010, has multiple drivers. I am well over 6 feet and the seat does not adjust low enough. My wife is about 5 feet and the seat does not go high enough. I can barely get in with the at lowest and most rear-word position. My wife has to add about 5" of still padding to the seat in the highest and most forward position so she can see over the dashboard. We have to raise and lower the drivers seat several times each day, as well as install and remove the extra seat cushion stack. We are retired and cannot have two cars and remain solvent.
I would recommend an un-weighted check of the seat height adjuster. That should confirm if it is working or not.