Have you had the airbox off lately?
Then you may have re-mounted it wrong.
One of the mounting tabs may be on the wrong sides of the bosses it mounts to
However.... Spree airboxes do tend to 'sag' away from the carb.
All the mounting screws need to be in place.
If that still doesn't work
Use some wire or duct tape to 'pull' it back into place.
And are you using the 'hoseclamp" that holds the boot onto the carb ?
Got to have that.