I almost fell over as Sabrina moved about. "Aha... looks like I've found the blockage..." I looked at ahead and there seemed to be a web of bubbles all struggling to get past each other. "Well... here goes nothing..." I approached the mass of bubbles and popped the nearest one with a pencil from my pocket. There was a noise like a great explosion, or a series of explosions, as the gas bubbles all began to pop.