I have a garelli super sport xl that leaks fuel from the bottom of the tank. When I noticed the problem and saw gas dripping I tried to wipe it away with a rag and a small rubber piece broke off the bottom. Almost looks like a drain plug but I don't know enough to even guess. Anyone know what this is/was? What the effect of not having it will be? Ideas for how to fix? The moped does start and seems to run well. Thanks!