hifi engine

Dark Sansui 9090

It`s dark! Everything else works,but the indicator lamps,and the scala for AM/FM is dark.I`ve cheked everything I am able to,but I can not figure out why this lamps do not work!All the lamps/fuses are ok,but they simply not get power!I suspect the source-switch,but how can this be cleaned whitout taking it out?
But then...I`m not sure of anything really,so all sugestions will be highly granted!
Mvh Rune