That would be NL51 with 43251 + 43317. Interestingly that set had to have 14 door changes prior to entering service.
Taking the information about 14 out of 32 doors requiring changing before this set entered service as accurate, combined with the amount of other work (presumably) undertaken before debuting on the MML, it makes one wonder just how LNER were allowed to continue to operate these sets right up to Nov / Dec 2019 in such seemingly poor condition.
At the risk of going over old ground these sets haven't suddenly become so bad in the blink of an eye since the end of their time with LNER. Many many issues must have been known about for quite some time in their final weeks and months on the ECML.
Were LNER "hiding" their true state of disrepair so as to be able to continue to use them for as long as they did?