"The astronauts changed several parts and repaired their main toilet this week," the spokesman said. Russian specialists had been unable to locate the cause of the problem.
Last week, a motor fan, used in space toilets to discharge waste into the proper container, stopped working while one of the crew members was using the Russian-made toilet.
The three crew members - Russians Sergei Volkov and Oleg Kononenko, and NASA astronaut, Garrett Reisman - had to use the toilet on the Soyuz space craft, which has a limited capacity.
In the fall, a new toilet is due to be installed on the International Space Station, replacing the current one, which has served astronauts for seven years.
The lavatory, which NASA bought for $19 million from leading Russian spacecraft-maker Energia, will offer more privacy for a crew expected to double from three to six by 2009.
The new toilet, which will have leg restraints and thigh bars to keep astronauts from floating away, will purify urine in six stages. The water will then be used in space for drinking, food preparation and washing.
Officials say the toilet water will be cleaner than U.S. tap water.
