Hello! Do you have a spare key to try? There are two possibilities here: Bad Key or bad Immobilizer Antenna (key housing).
If you have a spare key, start using that and see if the problem persists. If it still gives you problems with the other key, then the problem is most likely the Immobilizer Antenna (the fact that you can maneuver the Antenna and it starts supports this).
Since you already know how to remove the Antenna (the cover around the lock) you may want to start by replacing that first. The reason why I suggest that, is it sounds likely based on your symptoms, AND, its the only part you can replace w/o the Saab factory Scantool (even keys need the scantool to install).
I don't think it's the key. When I experience the problem, before I blow into the area where the key goes into, I always try the second key and that doesn't work. However, you state that by maneuvering the key housing resolves the problem. That doesn't do it alone. I have to blow into the area uncovered by the key housing and then it will start - thank god, everytime, first time.
Do you still think I should replace the housing?
Yeah, if you have two keys and they both act the same, then I agree, its probably not the key. Next time you are in a bind and the car won't start, press and hold the UNLOCK button on the KEY as you rotate the key to start it. The car should see a valid unlock from the key as a start attempt is made and bypass the Immobilizer (this will only work on keys that belong to that car).
But yes, I suspect that the Antenna (housing) may be faulty. Its just a guess, but based on the symptoms and what you do to make it start, I would say its very likely.