Failure of the positor, part of the circuit used to demagnetise the shadowmask at switch-on, is fairly common and can cause these symptoms.
It's an inexpensive part and usually worth having repaired.
Any products containing magnets (ie. loudspeakers), should not be used near the TV as they can magnetise the shadowmask, an integral part of the cathode ray tube.
An engineer can replace the positor and demagnetise the shadowmask manually if required.
Cobweb, January 2005
