Just finished the repair and thanks to Paul of how-to-repair.com (sent him a fiver). This dryer (TCM580) is only 4.5 yrs old but began making an annoying high pitched whirring noise from time to time. Eventually realised that it was coming from the small Chinese drain pump low down at the back. Paul,(mentioned above) has a number of useful videos and it did not take long to find the one I needed. Then off to ebay to search for a replacement - £16 as it happens which is considerably cheaper than the same thing offered on the Hotpoint web site for £48!!!. If I had got them to do it I would probably have been ripped off for over a hundred quid which is a bloody disgrace considering that these appliances should be fault free for at least ten years IMO. How long did it take me - about ten minutes once I had done the amount of dismantling which Paul shows
