To the point: My rubber stopper sitting in the top of my glass carboy is defective. That is, it wont.... stop. It keeps on wanting to slide out, so it's now perched quite precariously, kinda wedged just ever so slightly in the top of my carboy with the airlock in. However I am quite concerned as to it's stability. Any ideas as to what I'm doing wrong or what I could do? Cheers.