http://marsrovers.jpl.nasa.gov/mission/status.html
OPPORTUNITY UPDATE: Continuing Southward - sol 438-442, April 26, 2005
"Opportunity keeps driving southward and studying new locations despite a
disabled right-front steering motor. Opportunity has driven about 110
meters (361 feet) without use of that motor. The miniature thermal
emission spectrometer began returning good data again. That instrument
was in use when the rover stopped operating for a software reset on sol
440. The rover continues making scientific observations while engineers
diagnose the cause of the reset."