(03 Feb 2018, 1:14 pm)MrBoyt wrote I feel that this would be unwise until they can gauge the reliability of 9084 in service.
Also 9084 is out in service today, currently on a 67 which just departed the Metrocentre (according to the app...)
4899 was replaced at Riverside by 5216.
I would not expect 4899 to be withdrawn until 5216 returns to Riverside - it is currently on loan to Hexham (and has been since 25th January).