(Reuters) - General Electric Co GE.N said on Friday that turbine blade oxidation which forced Exelon Corp EXC.N to idle four electric power units in Texas also affects another model, widening the impact of the latest problem to hit GE's ailing power unit.

The logo of General Electric Co. is pictured at the Global Operations Center in San Pedro Garza Garcia, neighbouring Monterrey, Mexico, on May 12, 2017. REUTERS/Daniel Becerril

GE said the oxidation, which weakens metal turbines blades, also could affect no more than 75 of its 9FB turbines, in addition to some 51 HA-Class turbines that it warned earlier may have the problem.

GE said that the 9FB “comprises less than 1 percent of the company’s global gas turbine fleet” of 7,500 turbines installed worldwide. GE has said it sold its first 9FB in 2003.

GE shares were down 1.5 percent at $12.28.

The 9FB is part of a prior generation of turbines, known as the F-Class, in which GE holds a market share lead over rivals Siemens AG SIEGn.DE and Mitsubishi Hitachi Power Systems 7011.T.

For a graph showing GE's gas turbine market share and other details, click: tmsnrt.rs/2Fge6ra

The 126-year-old, Boston-based company declined to say whether any 9FB turbines have been shut down due to blade oxidation.

Industry experts and investors on Friday were trying to gauge the risk to GE power business, which has suffered steep declines in sales and profits.

News of the oxidation problem trickled out Wednesday when GE Power Chief Executive Russell Stokes mentioned it in a post on the LinkedIn website.

GE said on Thursday that while four HA-Class units in Texas had been shut down, 10 other HA units in the U.S. were operating. GE’s website shows five HA units operating in U.S. GE said the other five have not yet started commercial operation.