Starting about last June, I had white dots start to appear. They increased 2-4 per week, and by the time September rolled around it was bad, but not as bad as yours. I did quite a bit of internet research and decided it was the DMD. I bought Samsung 4719-001985 and it fixed the problem. When I replaced the chip I also took out the thermal blanket Samsung had behind the chip, and replaced it with a high grade thermal paste. One of the threads from other Samsung models had recommended this and it seemed a wise thing to do.
I either found or bought assembly/dis-assembly instructions and found them to be very cleaar and easy to follow. Using the instructions I had it dis-assembled, repaired, and re-assembled in under an hour, and 15 minutes of that was cleaned the old thermal blanket gunk off the board and applying the thermal paste. Note that the instructions talks about three alignment screws that shouldn't be touched (so don't).
When I turned the set back on, the alignment of perfect and no more white dots.
If you can't find the instructions on-line, email me and I'll send them to you, they are essential to doing it right.
I also spent 5 minutes on-line looking up prices and found the cheapest on Amazon, I bought mine from TVserviceparts.com which claimed they had the part in stock and then sent me an email saying it was back-ordered.
Hope this helps, John
PS I also called Samsung and they told me my set wasn't covered