Good luck with the dehumidifier.I suspect you may be right about the bearings in the BK blocks clicking and clacking as I get a little of this myself.I don't think replacing them is a major job and I would have no qualms about tackling it myself.Dismantling ballscrews is a very different kettle of fish and I wouldn't go near that one without a really powerful reason.I read some while ago that the balls are intended to vary very slightly in size so that they don't jam together and the differences are tiny.Which means it may not be wise to just re-insert them at random if they ever fall out.I have seen them removed by service engineers on a couple of occasions and they had a cardboard tube to slide into the centre of the ball nut to keep things in place.