Sent you an email. I thought so too about calibration but as mentioned, every once in a while at least one of these joysticks "loses it" and stops working. Re-calibrating makes it work again. The 're-calibration' process of course is just moving the stick into all 8 directions and pressing a button. I agree it shouldn't be necessary but I'm guessing the USB conversion/emulation is dodgy, since these aren't really "native" USB devices.
Email received, thanks. I'll answer as soon as possible. In the meanwhile, my guess is...
The chain is like this:
joystick -> OS <-> SDL ->Blastaway
The problem probably lies in the fact that something in the joystick -> OS part (I'd say the default OS drivers) make the joysticks look as if they were analogue. As a consequence, SDL and then Blastaway are told that the joystick are analogue.