I imagine those dwarfs really suffering badly from possession are put into a special area called Biggest Loser Housing, when Personal Strainers try to extrude faulty parts from them. Those that fail are broken and expelled to the outside world.
>
> The Dwarven approach to dealing with possession is quite practical.
> After a great deal of experimentation, various devices have been
> developed to siphon off the corrosive spiritual energy away from the
> surviving Inhibited Action Units, filtered through a thoughtquaduct,
> and used to enhance the sentient aspects of the machines involved in
> the Great Repair.
>
> As far as we know, Dwarven Exorcise Devices include the Great Exorcise
> Wheel, the Smart Bells (of various mental weights), the Medicine
> Bowels, the Cosmic Cycle Machine, the Brain Washer, and the Driving Me
> Up The Climbing Wall.
>