Hi Nino,
On the baseboard, those stacks of contacts actuated by the cam wheels, do you clean all of them and if so do you de-solder and disassemble them or use some other process.
On EM switch stacks - It depends on the condition. I disassemble each stack and then clean with alcohol or degreaser. I don't unsolder the individual wires as these machines have excellent wires and solder jobs from factory. I then reassemble and tighten the stack. Then adjust and gap each set of contacts.