Parts finally arrived, so got stuck into sorting the parking brake fail on the ML.
New rear cables, new discs, new shoes and new fittings.
Someone had been there before, and the backing plates are, er, showing their age.
It needs another tweak just to tighten it up a smidge. But it seems to be fundamentally functional and balanced. It should last the couple of years or so that the car has left in it...
Not sure how to address the smoking issue, driving it doesn't smoke at all, but sat idling it does produce a bit

If it's down to wear and tear, then that's fine, it's done nearly 210k. It also hunts a bit under light throttle, tooling down the road at 25/30 mph. It's not surging through the drivetrain, but you can hear it. Pulls like an absolute train though so reasonably confident it's not a real issue.