I'm guessing this is the reason Freightliner have an aspiration to 'overhaul' them before re-introduction. The more they iron out the little electrical niggles of a 55 year old loco, the more and more efficient it becomes.
Do we know what the difference between 66, 86 and (current) 90s distance between failures?
There were some rumours a few years ago of Bombardier making a UK-adapted version of its Traxx Electric locomotives, wonder if that can still surface...