TV screen has gone dim?

Hi I have a Wharfedale LCD37F1080P 6294406 but the picture has dimmed. Manually adjusting the brightness from 0 - 63 (max setting makes little difference. I've adjusted the mode and temperature colour again with little affect. I'm lead to believe it may be the inverter but I can't for life of me find a replacement part online. Does anyone have any help or suggestion?
Cheers Ian