You should be able to get Caig Deoxit at any electrical supply place. It's not cheap. Something like $10 for little spray can the size of a whiteboard marker. It's safe for the plastic in MB cabin switches.
The 83 380SEL is nice in that both ends of the fuse holder are visible. Later models have one end buried in a pit. Maybe take a dremel to those is you want to clean them mechanically.