My suspicion would be either a crack in the section/feed or maybe the converter (I don't own one of these but Googling suggests it takes a converter) - test components separately? Best case is that the converter has gone belly-up and you can replace it. "Burping" ink is a known phenomenon, especially with air pressure changes (e.g. air travel), but IME that's more common with eyedroppers/similar. If the issue is in the section/feed, you're probably better off getting a new one at this price point.