Sony KP-57WS500 57" Rear Projection Television "potentiometer failure" Questions

...I've had blue lines. If you take the whole front speaker grill cover, there is a Red, Green, Blue potentiometers that can be

...failure, you must take front panel off, rectangular cover under it and gain access to CRTs. You will see 3 picture tubes with wiring and boards attached to them. on a bootom of the set there is a ...