whine whine whine...

We use the same system in Oakland, Alameda County, California. Five suggestions:

Yes and No check marks look the same; make them different. Perhaps happy and frowning faces (or thumbs up and down) and green and red color coding.

One measure or race per screen. I found it to navigate from measure to measure on one screen; on mine you went top-to-bottom in one column, then left-to-right. My first inclination was to go left-to-right like English.

Option for "more info" about each measure or race, from the summary perhaps. Measures are notoriously misnamed. You shouldn't assume prior exposure to campaign literature.

Add a navigation bar listing all the measures/candidates, showing progress, allowing you to flip through the ballot. Also takes some pressure off of making mistakes.

Print a receipt, perhaps even a copy of how you voted, to take away.

I served as a poll inspector at a precinct in Oakland. In addition to Phil's good observations, I have a couple others

1. Card slot it too small. Many voters had trouble inserting the card in a 1/4 inch thick slot at waist level. ATM slots are much closer to eye level, which makes life easier for people.

2. I cringed as various people sneezed and weezed at the booth, likely sending at least a few fellow healthy voters using the booth later home with colds.

3. Some elderly voters were unable to touch the screen with a steady hand. Thus, they would touch one part of the screen with their index finger tip and another part with a another finger unintentionally. This sent more than a few voters to the write-in screen, leaving them confused. -- Solution: The Registrar provided q-tips for people to touch the screen with, allowing those with shaky hands to have a pretty accurate pointing stick which keeping their hand far enough from the screen to prevent mis-touches.

4. If you accidentally checked a box, you had to touch the same box to undo it, like a toggle. For instance, once selecting Candidate A by mistake, all the boxes for Candidates B, C, and D would disappear until you touched Candidate A's name again. Kind of confusing.