It might be possible for the converters power factor to have gotten worse than it already is. The WFCO converter like many switching converters has a really lousy power factor which effects non inverter gens. Normally it is not a problem but perhaps in your case either the converter has gotten worse or for some reason the gen is more susceptible to the problem. I don't think you have much of a choice here but to replace the converter. In your case I would replace it with a converter that is power factor corrected.
Sam
