actually required for sale, so that it would have enough replacements for faulty machines. Similar problems were reported in the US market, where contemporary reports suggested that only a third of the ZX81s shipped actually worked. However, figures released by Sinclair claimed that only 2.4 per cent of pre-assembled machines were returned, although 13 per cent of kits were returned. Clive Sinclair strongly denied any problem with reliability: Sinclair attributed the higher failure rate of the kits to customers breaking the components by inserting or soldering them the wrong way, though the company admitted that there was a persistent problem with power supplies that affected both kits and pre-assembled ZX81s. The bigger problem was perhaps Sinclair's lack of after-sales service, which Robin Clarke of New Scientist described as "one of the worst after-sales performance records of any company ever established." The Financial Times observed that "Clive Sinclair's offices are filled with returned computers which can take months to be repaired." The company's slowness in replacing returns and delivering freshly ordered machines meant that Sinclair Research gained a reputation for poor customer service. Marketing The marketing of the ZX81 was handled by Sinclair's long-standing marketing agency Primary Contact (now part of Ogilvy & Mather), which had provided marketing services for Sinclair since 1971 and was to continue doing so until 1985. Sinclair's entry into the nascent home computing market gave Primary Contact a major challenge – how to market a product simultaneously at hobbyists and at the "man on the street", who probably had little or no computer literacy. The answer was to pursue what the journalist David O'Reilly of MicroScope magazine described as a single-minded "user-friendly strategy." Chris Fawkes, one of Primary Contact's directors, explained: "We brought personal computers to the mass market by showing that you didn't have to be a whizzkid to use one." As Clive Sinclair put it in a 1982 interview with Your Computer, According to Ben Rosen, by pricing the ZX81 so low, "Sinclair has opened up a completely new market among people who had never previously considered owning a computer." Clive Sinclair acknowledged the role that guesswork had played in his decision to launch the ZX81 on such a large scale: "It was a surmise that the man in the street would want such a computer. He does, and our information is that a lot of people are using the machines avidly." A New