We recently replaced the bulb and the controller on a ThinkPad R40. We had the same problem and we purchased the bulb first, but the problem persisted so we purchased the controller. All Parts +S&H was around $60. It was worth it because we are comfortable opening the screen, but we had lots of screws to keep track off and what goes where. You will be able to find in the online manual how to replace the bulb and the controller. We bought the bulb at www.lcdparts.net, can't find from where did I buy the controller.