SEPTA is tasked with doing an intensive, invasive inspection of every single component on its troubled Silverliner IV fleet.

"Every electrical connection, every lug, every contact tip, every circuit breaker," Greg Buzby, a Regional Rail engineering manager with SEPTA, said. "Everything is getting a wrench put on it. A visual inspection, is it loose? Any signs of arcing or heat damage?"

The U.S. Department of Transportation ordered top-to-bottom safety checks a week ago in the aftermath of five fires on the model in the Philadelphia area since February.

SEPTA says it has a handle on how the fires started, but its general manager tells CBS News Philadelphia inspectors haven't uncovered exactly what could connect them.

A force of workers continues its deep look inside the Overbrook Maintenance Shop in West Philadelphia.

"All 225 cars must come through these facilities and be inspected," SEPTA GM Scott Sauer said.

The work, mandated to be completed by Oct. 30, has created a scheduling nightmare for Regional Rail. More than half of the Silverliner IV fleet is out of service, and that's spelled a slew of delays for passengers. SEPTA has faced withering criticism.

"My message to staff is exactly that, the buck does stop with me," Sauer said. "But we have an obligation as a team to put out the best product and the safest product."

Buzby said that despite the age of the Silverliner IV cars, they're mechanically easy to work on and maintain.

"You can rebuild the components that with modern-day electronics, you can't," Buzby said.

But with a harsh spotlight from federal railroad regulators over railcar fires and a public relations firestorm due to cancellations, delays, increased fares and service reductions, SEPTA is sensitive to customers losing faith and finding a ride elsewhere.

"We have to get this right, and get this right with urgency," Sauer said. "We have to make it right so our customers can rely on us almost every day."

SEPTA said at least 10 rail cars have passed the enhanced inspection, with many more to go.

Officials say they'd replace the whole fleet Friday if not for the $2 billion price tag.