thanks guys for your feedback.
the light leak on mine is quite visible right at the level of my head, that's how i came to notice it in the first place. if i raise my hand or leg during the movie, it will be lighted up which is annoying. the rest of the time i can see the shadow of my head casted on a cushion if i hold one during the movie.
I cant find the hc4000 filler mod posts, give up.
Mitsubishi sent a technician to check mine today. he said the leak is normal due to the design of the DLP chip. he has arranged for a new unit to be delivered to me and let me choose a better one between the two, but he has warned me that the new unit might be even worse so it might just be a waste of my time after all.