Fan switch only works in one position?

[cp99]

The rightmost fan switch only works when set to right position 4, i.e. the highest. The other positions does not turn on the fan and sometime the radio shuts off when you change positions.
Is this something that indicates a serious problem or could it be something simple like dirty contacts behind the switch? I guess either way you have to dismantle all of the plastics around the front to access it?

The model is a Laguna Sport 1.8 yr 2000.

Thanks!