My outboard leaks water in from the bottom part of the powerhead enclosure. There is a rubber seal around it that seals to the lower unit, but it is not tight. When I take the top cover off I can wiggle the bottom part a little bit. There are four bolts that hold it tight, but that are all as tight as they go. There are also rubber bushing things that hold the bolt up (i think), but they seem to be connected on the bottom somehow. What should I do to get this to stop leaking?