I seem to have some difficulty with the swift transformer/charger panel. From reading the swift owners manual my setup is not the same. The panel in my van has a row of fuses behind a perspex panel which i noticed that one of the fuses is either blown or not sitting in place. How do i get this cover off to replace the fuse. I tried running the lights, but although they go on there is a loud humming noise which appears to be coming from under the dining seating?. As this is my first motorhome I am a complete novice. The owners handbook is not much help to be honest. Am I assuming that the lights only work off the leisure batteries?