Updated from 8:25 a.m. EDTGuidant ( GDT) shares fell again Friday after the company late Thursday confirmed that its experimental drug-eluting stent Champion has run into quality-control problems that will delay its launch. UBS responded by lowering its 2005 earnings estimate for the medical device maker from $2.67 to $2.60 a share. The consensus estimate is $2.68 a share. The broker also says it does not expect U.S. regulatory approval of the stent until the first quarter of 2007, at the earliest In a special conference call to discuss the state of its stent, which is used to treat clogged arteries, Guidant yesterday said it is making refinements to its manufacturing processes and will be improving the overall quality of the device. The moves will delay the company's plan to file for U.S. approval for the stent by six to eight months, pushing off its filing date until the first quarter of 2005. Shares were off 49 cents, or 0.9%, to $55.01, after falling 38 cents Thursday. Five weeks ago, Guidant warned that a limited number of stents failed to meet the company's performance standards or quality standards in preclinical trials. Guidant discussed the quality-control issue with the FDA and said it has structured a plan that will not require the company to perform further testing of the stent. Competition in the stent market is heating up, and Guidant doesn't want to fall too far behind rivals Johnson & Johnson ( JNJ) and Boston Scientific ( BSX), both of which already have stents on the market.