Jack a couple of things you can check, with the motor turned off can you rotate/move the blade/cutting bar, I'm looking for a seized deck bearing or something stopping the cutter from rotating. We are trying to work out iff the motor is stalling or being killed by an ignition cut off, they have a different reaction. Another question, does it stall if you attempt to drive. If none of the above it is a safety switch on the cutter somewhere