I've got a 500 watt Redi-Line generator. Takes 12 volts, and spins a coil and so it is suposed to make sine wave output. Used it in my locksmith van for many years. Stopped working a couple years ago. Just does nothing. Doesn't kick on, hum, or anything. Should I pursue repairs, or just pitch it? Or take it apart myself?
Theoretically anyone who works on largish electic motors ought to be able to take a good stab at fixing this, unless it's the regulation circuitry that's dead...
Given that solid-state modified-sine-wave inverters are fairly cheap these days, and MSW is close enough to sine for most devices to tolerate, I'd say price those before you commit to repairing the old motor/generator box. They're more efficient too... and the power in the van all comes from the motor eventually, so efficiency does matter.
(I think I spent about $150 for a combination of gel cels and a cheap MSW inverter -- the latter can be plugged into 12V directly, or I can strap it to the gel cells and get about an hour's worth of 300W AC out of it if they're fully charged. More if I'm not drawing that much power. I wouldn't recommend this particular unit -- it's greatest advantage was that it was so cheap -- but $200 will buy something similar from a more reputable brand.)