That voltage is very low.
Might need to replace the Rabbit Switch.

Before you dig deeper into the Rabbit Switch, you have to take a close look at the 4 small switches that click when you rotate the Twist Grip.
They might be arranged in groups of 2, or they might be all next to each other.

These switches enable the travel function to work.

For now, ignore the Rabbit switch, and focus on those 4 small switches.
There is a chance that the 3rd speed switch can't close.
There is a small screw directly above the Red or White colored button of each switch.
If you carefully turn the screw clockwise, of the 3rd Speed Switch, then you'll be able to hear that switch click when you rotate the Twist Grip either full Forward or full Reverse.

Please be sure to have the Drive Tire above the floor.