Hi Lucy, I have a Bush 2137TSIL TV with a similar problem, looks as though the degaussing thermistor has bit the dust. Its a small inexpensive device 2 or 3 pin, im not sure what mine is as I havent opened my tv yet but its most probably a small 3 pin.They cost about £4. Im in the process of looking for a replacement so as your problem sounds the same, if you can post the model number of your tv I will see if I can find where you can purchase the replacement part.
Alan
October 2009