I've bought a lot of stuff from Omega and they service also although they are always backed up on service work. Oil pressure switches can get gummed up by dirty sludgy oil so keep clean oil in the engine. After oil change remove the oil pressure switch and flush it with diesel. While it is out crank the generator over until clean oil spurts out. Then reinstall the switch. The hard starting is generally caused by not following shutdown procedures of turning off the fuel and letting the engine die from lack of fuel. If you just turn the key OFF fuel left in the carburetor will gum up the jets and float in between uses. shakey
Also, petrol and diesel degrades over time. Diesel & petrol last for 6 to 12 months in a tank. so if you haven't used your generator for over a year, replace all fuel.
