MARC train riders shouldn't get their hopes up too much but there just might be some good news coming their way.

According to Amtrak spokesman Steve Kulm, the national passenger railroad just recently returned the first of MARC's four AEM-7 electric locomotives to the Maryland Transit Administration after almost three years of being laid up in a repair shop in Wilmington, Del. He said a second locomotive is expected to be returned to  the MTA late this week or early next week.

Kulm said Amtrak believes it has found a fix for a vexing electrical problem that has sidelined the locomotives and hope to have the remaining two returned to MARC before the end of the year.

A shortage of electric locomotives has been the main reason that MARC has been forced to run short, crowded trains on the Penn Line in recent months. When too few electric locomotives are available, MARC has to substitute less powerful diesel engines that can pull fewer cars. The locomotive shortage also leaves the system vulnerable to breakdowns that can force train cancellations.

The return of two locomotives might not seem like a big deal until you look at it as 20 percent of MARC's fleet of electrics. With the four AEM-7s in the shop, MARC has had to rely on its six HHP-8 locoomotives (known as Hippos) -- a model with a less-than-stellar record of avoiding breakdowns.

Maryland Department of Transportation spokesman Jack Cahalan confirmed that the MTA has been putting the returned engine through a round of testing and that so far it has passed.

"The phrase cautiously optimistic is one you will hear repeatedly from us," Cahalan said.

Stay tuned. We hope to have more details in Thursday's Sun.