Hi Listerix, and welcome. Congratulations on your recent purchase. The fuel control solenoid is a 12 volt unit it has two coils and a small built in relay, it can be overridden using the lever on the front of the engine, lift the lever up and lock it in the run position using the spring loaded pin. The decompression solenoid is a 240 volt unit and act against a spring, as the engine spins up during battery starting the generator head starts to produce electricity which disengages the decompression lever, allowing the engine to start. This can also be operated manually by removing the spring.
All spares should still be available from Gary (Dieselgman) who runs Diesel Electric Services in the USA.
Good luck,
Bob