The contactor is an automatic switch that selects either the power from the shore or the generator. The manual switch does the same job, just manually. I bought a Schneider Electric rotary switch rated for 32A, with an off position between the shore and generator position. It is inside the same box in the cockpit locker, except the selector is inside the galley to port of the existing generator start switch.
My Stator was rewound for 610 euros including VAT, and was assembled (with difficulty) in the engine room. It all works now. I also installed the 20A bipolar trip switches in the aft lazerette that Bill suggested, and I took the opportunity to replace the full length of the shore power cable (right up to the rotary switch).
All the electrical work was done by an electrician.
Super Maramu #151
Currently in Cagliari, Sardinia, Italy.