Due to their age etc the Switches can cause problems due to dirt, corrosion etc of the contacts. They are easy to repair. Due to their age the plastic can be brittle so take care. If they are cold it will help if they are removed and warmed slightly, i.e. placed on a radiator for a short while. As with all things electric make sure that the battery has been disconnected before starting any work on the electrics.. The terminals on the switches are numbered so make sure you make a note of what wire goes to what terminal. When reassembling the switch can be put back together upside down so mark the switch to ensure correct reassembly. When the switches are taken apart there are no springs to suddenly fly out and disappear but take care as you will want to see how to put back correctly. All the switches come apart the same, the only difference is the number of terminals and the number and type of contacts, see below. When levering off the rocker top of the switch gently release one side, hold in position while levering off the other side.
The internals of the switch look like this.
Clean all contacts.
The switch shown has contacts as seen. Some of the switches have contacts
in the center. These contacts are not round as above but narrow. The rocking contacts
pivot on the contacts, make sure you clean these. There is no need to apply grease etc.
Just light lubrication. A squirt of something like WD40 on a rag and a wipe over is all that is needed.
As all the good manuals say assembly is the reverse of the above and in this case it is true.
Good luck and I hope it helped.