Bachmann have advised against feedback controllers and electronic HF track cleaners since their fitting of DCC sockets, and the latter may well destroy decoders. I've had no problems operating in analogue with blanking plugs fitted or the socket and electronics entirely removed but this has all been with conventional motors. The resin innards of the tiny cheap coreless motors used by DJM in their own and commissioned products will melt if heated so that makes them prone to damage from HF track cleaners and the regular feedback controllers designed for conventional iron core motors. My understanding is that Bachmann have stayed with conventional motors except for a tram model and possibly the new Wickham trolley. 

Thanks Clive - very helpful info. I have operated Bachmann, Hornby and Heljan locos for a few years without any problems, but now a little wary of the new locos from DJ and Dapol. Not sure whether to just take a chance or not; don't really want to give up the track cleaners as they do work so well.