This past summer, i visted Cedar Point and watched this almost happen to a train on Dragster. It was going up the tower noticeably slower, and then right at the top it almost came to a stop, barely made it over haha. A rollback happened shortly after, and the next day the ride was closed until about...

Carowinds
Gillians Wonderland Pier
Castaway Cove
Busch Gardens Williamsburg
Six Flags Great Adventure
Six Flags Magic Mountain
Cedar Point
Kings Dominion
Islands Of Adventure
Darien Lake

if you'd like to see more, https://www.flickr.com/photos/39414003@N04/

1:17 AM.