Installed a water pump kit on my 2002 90hp Johnson. All went well. Trying to replace lower unit, cant seem to get exhaust housing gaskets where they need to be. Paying close attn. to water tube as i slide things back together, exhaust housing gaskets dont stay where they should. One or both gaskets move out of place when i try to position things where they need to be. Any thoughts on how to keep gaskets in place while installing lower unit?