When you go up to sort him out, have you an oscilloscope to take with you? this will show exactly what the sine wave is or isnt. apart from your usual meters etc. also if youve any water immersion heaters handy take one along as well to replicate load switching. the more amps the better. obvciously youll need a water tank to put it in first. Running electronic kit of generators can be tricky. We have several here as no grid supply, and recently aquired an inverter based plasma cutter. Works perfectly of the grid at a local factory, try it on a 6kw generator? wont cut 1/4 in plate. Yet the same generator will run an oil immersed welding transformer at a 70 amp welding load all day. grunts a bit tho. Ted Frater Dorset UK.