Need help please: I have had the Toro Z5000 for about four years. The other day I went to mow and it cranked right up just like always. When I got out in the yard, I thought I smelled something burning. I thought either a belt or maybe it was low on oil. I rushed back to the garage and shut it off. I removed old grass to check belts and sprayed water to removed a bunch of old matted grass. I even added a little oil since i couldn't tell if it was low or not since the engine was warm. Now, when you turn ignition, starter just clicks. I have checked PTO switch, checked both fuses, bench tested solenoid, bench tested main kill switch, both arm lever switches, and had battery checked just in case. I replaced the solenoid just to be sure. Also, the battery is about two months old. Just in case it matters, the voltage drops from 12 to 7, when the ignition switch is tuned over and you hear the click. I took the starter off of the mower and bench tested it. It engages in and out and spins like i think it should when power is applied direct. Put it back on the mower and it never turns over, just clicks. It seems to stay engaged and never disengages. There is a PTO clutch/brake switch on the bottom of the shaft, underneath the engine. I disconnected and cleaned with air compressor as best that I could. I don't know if that did anything, but I'm not sure what else to do with it. Does anyone have any ideas?