And the press release from Amtrak:
The full press release can be found here.April 17, 2005 8:00 EDT
On Monday, April 18, Amtrak will substitute Metroliner and Regional trains for approximately half of the cancelled Acela Express trains between Washington, New York and Boston, re-accommodating passengers on these trains as seat availability may permit.
Additionally, following the successful inspection of one Acela Express trainset by Amtrak and federal safety officials, Amtrak has cleared the train for service. It will operate tomorrow as #2109 departing New York at 8:00 a.m. and as #2168, departing Washington at 2:00 p.m.
Operation of the Acela Express trainsets was suspended Friday, April 15, following the discovery of cracks in brake rotor spokes Safety is Amtrak's top priority and no trains will operate unless fully inspected and found to be safe for service.