Hi, If its the same make-up as my panasonic 40" rear projn, you can undo the screws at the rear of the top section, along with unclipping the plastic panel bearing the "panasonic" name which is under the screen on the front of the tv. this gives access to another 4 screws which allow you to take the whole front off and see (1) the mirror - (which needs to be spotless) and the 3 projection bulbs underneath it. - It you look into each you should be able to see the picture and the "obstruction" - it may be on the focusing lens, or underneath on the element itself. - If its just dust on either this can be wiped off with a soft cloth, but if you can see stuff floating around in the oil filled fluid which is in each element, you will require to clean the respective element. - This is where I got to when I dislodged some of the dirt which had gotten into mine and made the picture worse. - I came to this sight to see if there is a way to drain and replace the fluid. - Thankfully the mix is listed, and I intend to syphon off the crap contaminated stuff and replace it with new. Hopefully, yours is just dust though.
Colin Dick
November 2007