CAPE CANAVERAL, Florida - NASA says a switch box removed from space shuttle Endeavour has a blown circuit.

The repair work is taking longer than expected. That means Endeavour's launch on the next-to-last shuttle flight may face yet another delay. NASA currently is targeting a launch for next Tuesday at the earliest.

Endeavour was supposed to blast off last Friday. But fuel-line heaters did not turn on during the final part of the countdown. The problem was traced to the switch box. A replacement was installed Wednesday, but more testing is needed.

Endeavour's final voyage is under the command of Mark Kelly, husband of wounded Rep. Gabrielle Giffords. She plans to return to Florida once the launch is rescheduled.