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.