I have a Hitachi DLP 50V720 ..The original lamp was blown(Broken) and replaced with an aftermarket lamp which was 2thirds cheaper than a factory original. After turning set on there is a green blotch in the center of the picture. Also noticable is almost no effect when adjusting the contrast or brightness...otherwise i can still see the picture. Could this be do from not installing the factory lamp instead i used a cheap lamp off ebay.The picture was fine before the lamp failed. Thanks, Roger