Chipco had been using pelletized polyester resin from General Electric to make their chips. They changed to a different supplier who had a lower price. The chips made from the new supplier's resin originally looked fine, but they faded badly after a period of time. Chipco made new chips with different resin and replaced all those that the casinos complained about. Chipco sued the supplier of the resin that appeared to cause the problem. As best I can determine from the court records, Chipco won a judgement of around $800,000 to cover the cost of the million chip replacement program.
There are still lots of these faded chips around in collectors' hands. Some are nearly all white by now [g].