I just acquired a Z445 z-turn mower. It will not start with the ignition switch. I can jump across the solenoid to start it, but as soon as I move the control handles out of the neutral position it will cut off. I have replaced the ignition switch and tested the seat switch (which tested good with a meter and physically). The PTO will engage, and I hear a clicking near the carburetor area when I turn the key to the on position. Any ideas? I do not have any manuals for this mower.