Hustler/Honda starting issue

Have you checked all the dead man, blade engage, brake/clutch switches? You can wire around each one temporarily to see if your voltage returns to 12. If so, hook each one back up one at a time to see which one is causing the problem. Also, test your voltage regulator while you're at it.

Bertsmobile is absolutely correct about the Bendix retainer clip and the little circle retainer clip holder. Don't lose them.

Something you should check about the starter motor are the bushings and brushes. All of the switches could possibly be good and if the bushings are worn to the point the starter motor is dragging under load, it won't matter what all you replace if the problem lay in the bushings or brushes. Brushes can cause a slow starter motor under load as well. If one brush isn't sitting flat on the armature, it won't give full power. Now, you should have about all the information you can digest for starting a motor.

Again, good luck.

Install Starter assist kit #107910