PORTLAND — Amtrak’s Downeaster has restored its full schedule of five daily round-trips between Portland and Boston after track defects detected months ago led to delays and cancellations.

Patricia Quinn, the executive director of the Northern New England Passenger Rail Authority, said in a statement that the service restored its full schedule on Friday.

“We especially want to thank our riders for their patience and understanding while necessary improvements were made along our tracks,” Quinn said in a prepared statement. “The safety of our riders is of utmost importance, and the tracks were in need of repairs after the long frigid winter.”

The repairs were required after the Federal Railroad Administration placed “slow orders” on about 27 miles of Pan Am Railways track — running from the Massachusetts-New Hampshire border to Maine — in about 25 different spots.

The delays were long enough that the service could not maintain its regular schedule, leading it to cancel about 43 trains from Boston and Portland in July alone, according to the industry group TrainRiders/Northeast.

The repairs also put a dent in the train’s on-time performance, which dipped to about 19 percent in June, when revenue and ridership also dipped compared with last year. For the service’s fiscal year that ended June 30, the Downeaster had a slight increase in revenue, however, up to $8.62 million from $8.1 million in 2013. Ridership for the full year was up for the year to 536,524 from 512,775 during the previous year.