They were initially due to end service on the EC and accordingly maintenance was run down on them. Now that the service life is being extended they need to be brought back to an acceptable standard for that...having seen both the old EMT and the 'new' EMR HST sets I can assure you there is a significant difference between the condition of them.
Thank you for that. It's certainly the case that the 'old' EMT sets were in good condition - I posted, on the 'Off lease HSTs' thread interior pictures of NL07 taken in service very shortly before it went for scrap, and it was faultless, but I do know the reason for their replacement.
However, it does seem a bit odd about the LNER ones; their last run on the LNER may well have been on an up Scottish express, non-stop from York at a steady 125 (ish) and suddenly they're unfit for use without major work. I'm sure that they weren't all stopped when they hit exactly 10,000 hours (or whatever the parameter is nowadays).
I also hope that the LNER sets, like the old EMT ones, have the nice new (laminated) windows that you can see out of and not scratched by 40 years of washing-plants!! But I don't know I'll ever get the chance to travel on one, with leisure travel being discouraged.