occasionaly (3 times in last year) when starting the car, instead of cranking over I get a buzzing/arcing kinda sound from inside and just right of the far left heater vent.

I posted this in general engine tech too. Figured I'd check here before I start tearing stuff apart and see if anyone else has had that problem and what the cause was.

(An extinguisher is in the car within easy reach just in case)

 

Drop the fuse panel down and see if you might have a connection grounding out inside there.