On return to Didcot, it was found that the firebox and boiler stays had broken, resulting in the need for a large amount of remedial work to the boiler. On 6 September 2012, the locomotive was moved to Loughborough on the Great Central Railway for firebox repairs, which were completed during early 2013. The locomotive then made a series of appearances on the Great Central Railway, for both testing and running-in purposes but was later returned to Didcot where it was to be prepared to operate on the main line. In 2014, the GWS was given derogation by Network Rail to use a portable GSM-R radio unit on 6023. This unit could then also be used on other GWS locomotives yet to work on the mainline, such as 2999 "Lady of Legend" and 4079 "Pendennis Castle".