What's funny about the most recent sequence of posts is that, try as I might in conversation, I can't get very regular users of the Inverness sleeper to register the slightest interest in the implications of unreliable traction. Their view is that it gets through 99% of the time and that they can't think of a recent occasion when they've been inconvenienced by a motive power or ETS problem. If they have been in the past then they've got longer in bed and are quite happy with that.
Maybe the 73s are rubbish, but I can't seem to find any reports of serious dismay, presumably so long as the 66s are doing the business alongside them.