1973 P337 Factory Recall?

[Multimotor]

According to Aviation Consumer, at http://www.aviationconsumer.com/issu...er_7278-1.html

"For example, the pressurized Skymaster was initially such a disaster that the first year's production was recalled to the factory for complete remanufacture and modification."

There is no citation for this comment, and I can't find any other evidence of that happening, either here (with my search challenged skills) or on the internet.

True? False?

If true, what specifically was done during the "complete remanufacture and modification"?