Still being new to my Speedmaster (2004) I was doing an oil change yesterday. I noticed that there are 3 rubber tubes that come down behind the oil filter. One is close to the oil filter and 2 look as though they come from the air box area. I have looked in the Haynes manual and can only find reference to one tube that is a drain tube. Can anybody tell me what these tubes are for and should they have plugs in them?