Karl:

I have an '81 (non-California) air-cooled.  When it
doesn't start right up when warm, it is because it is
flooding.  So I start with the pedal to the floor to
give it max air.  But if it doesn't start right away,
it is flooded.  I have a switch to turn off the fuel
pump, so I crank with the pump off for a couple of
seconds until it starts to catch, turn the pump back
on and off I go.  In mine, it starts cold and starts
hot, but sometimes doesn't start "warm"--when it has
been cooling down for ~30 minutes or so.

So besides checking/replacing the temp sensor on the
head, I'd figure out whether it is flooded or not
when it doesn't start and go from there.

Richard