If it's what I think it is, it will just take a few seconds to fix.
First, refer to your parts diagram - if you don't have it, then refer to this: http://www.badger-airbrush.com/100ilparts.htm
From your description, it seems most likely that part 50-030 (tube shank) isn't screwed in as far as it should be.
Unscrew the handle and loosen (but don't remove) the needle lock nut (51-010).
Turn the tube shank clockwise until it engages the trigger and lever. Do not over-tighten or it will lock the trigger up. Re-seat the needle and tighten the lock nut. Re-attach the handle.
If all is well, that should be all there is to it.