Some three years after it first surfaced, IBM has finally tracked down the contamination problem that has plagued the original 2.4Gb A04, B04 and AA4 models of the 3380 disk drive – and is in process of replacing parts of the air baffles or the entire head-disk assembly in all 40,000 or so of the drives out in the field. According to Electronic News, the company has finally traced the problem to the Bromine and Antimony used in the fire retardant, which can break down and contaminate the heads, causing crashes. Gartner Group estimates that the replacement and servicing programme will cost IBM upwards of $100m. The problem does not show up on the newer D models or the double capacity E models; the models that are affected are no longer in production. According to the US trade weekly, the replacement programme began in September, and typically takes four to six hours per site, which can be a major problem for large sites. Although the replacement programme is mandatory, some users are refusing to co-operate: Xerox told Electronic News that it would suffer 160 hours of disk downtime, and was not prepared to have the work done. Advanced Micro Devices, with 38 of the affected disk units, said that half of its drives needed the entire head-disk assembly replaced.