I have a four year old John Deere LX266 with 200 hours on it (Kolher 16HP). It was mowing fine today. I went over a small bump and the blades disengaged... just stopped rotating. Pressed and re-pulled the PTO, blades would not engage. Engine running fine but cant get the blades started PTO is not working. Shut tractor and attempted to restart. Now it wont start at all. Seems the PTO is engaged and tractor wont start. I thought I Detected a slight burning smell. Checked brake switch, doesnt seem to be an issue. Seat shut off switch also not an issue. Headlights work. Turning ignition key causes idiot lights (oil and battery) to light up. Turning key produces an electrical noise pulling the PTO out stops the noise, pressing it back in causes the noise to return. Dropped the deck but tractor still wont start. Engine does not turn over at all. It seems either the PTO switch has gone bad or the PTO clutch has gone bad. Im inclined to think its the PTO clutch since it happened as I went over a bump. Has the clutch gone bad or is there a possibility that the PTO clutch wire is shorting out? Does anyone have some trouble-shooting tips to determine whats happening? Causes Im considering: 1 PTO clutch wire not grounded or unplugged. 2 - PTO clutch went bad 3 PTO switch went bad. 3 Fuse issues. Not Considering: 1 Battery or ignition switch issues lights are working, dashboard lights work. Ignition produces lights and noise. Tractor ran after blades quit but would not restart after shutting off. Problem is associated with the start process (safety issues)?