At that time Deltics were generally run with only limited maintenance until they became unable to continue running and required rescue by other locomotives after breaking down. Typically the cause would be engine failure, although some Deltics were withdrawn for other reasons. Exchange of operational power units between withdrawn locomotives and running examples was regularly carried out at both Doncaster Works and at Stratford Works. Withdrawn locomotives were then taken to Doncaster Works for stripping and eventual scrapping. For a time the Deltic scrap line was a major draw for railway enthusiasts.