I've just had the same problem with mine. Searching the net turns up quite a few people with similar problems. There are components in the power supply called capacitors, and these can fail, especially if you have taken the power down. (Mine failed after a power cut.) It's apparently repairable if you know what you're doing, but you need to be competant at soldering small electronic components. The average electrical repair shop might not be too good at this, as they tend to just swap circuit boards out. If your machine is out of guarantee, you need to find some backstreet techie who will tinker with it for you for not too much money. Paying a high street repairer to take this on could well cost a packet. Given that a replacement machine will be at least £250 (UK), if you can find a back street boffin to do it for you, you'll be laughing.
Robert Day
September 2011