I need to change the filter for my power steering and the leveling switch for my self-leveling suspension on my ’89 750iL. Can someone explain how to go about doing this? My right side power windows are also malfunctioning; the right front switch works the right rear window while the right rear switch works the front window. My local BMW dealer said the switch is ok that he suspects I need a “GM” replaced and code. Does anyone know what he is talking about etc? Please help!