Have you checked your ignitor? You may have a bad glowplug.
Take the glowplug out and see if it glows in your ignitor. Also,
while you have the glowplug out, turn your motor upside down
and see how much raw fuel spills out of the glowplug hole in the
head, the motor may be locking up because it's flooded. Just a
thought, but it's worth a try.