Zero Turn Mowers

Hi, I have a mz5225zt with 145 hrs. on it and there is an intermittent start problem. Purchased on 05/21/12 and taken in for repair for this problem on 10/29/13. Repair was made but not trusted. Unit ran fine for remainder of the season (12/30/13)and properly stored. In March of this year the unit was take out of storage and run several days before the unit would not start again. How do I check the wiring, switches (connections ect.)and solenoid for failure?