More than likely it's the 12v motor itself that has failed. Since you've found the solenoid, you can follow the large wire from the solenoid that goes directly to the back of the 12v motor. Using jumper cables and a known good 12v battery, you can attempt to jump the motor directly by placing the ground cable on the motor housing and the positive cable directly to the lug on the back of the motor.
** If the motor runs, then your problem is in the solenoid OR a bad power/ground feeding the solenoid.
** If it doesn't run, then you know the motor is bad.
The RVA leveling system is my favorite leveling system of all time. Due to it's simplicity and quality parts used they are perhaps the most troublefree leveling system ever made. They've only ever used 2 different 12v motors to power their hydraulic pumps and they are readily available most anywhere.
Have a look here: http://www.rvajacks.com/pl_5.php