I just had to replace the lamp in my 18 month old 73837, and all I can say is Wow!
I'd been very pleased with the picture, and had dialed it in pretty well, I thought, over a year ago using an X-Rite meter and CalMAN. The one thing that nagged at me was that I thought the picture could be a bit brighter. The best readings I could get for overall luminance were ~22 to 24 fL. But, the grey scale measured very well, the colors were good looking, and the set was very nice to watch. When people would come over, they'd invariably remark on what a great picture the set had.
Then I recently got a new smaller screen for the bedroom, and it's a backlit LCD. It seemed very bright, and I wanted to see how I could dial it in, so I hooked up the meter to my laptop. The luminance out of the box was reading 75 fL.
It had seemed to me that the 73837 had been gradually getting less bright, but gradual changes aren't quite so noticeable. But when I now measured the luminance again to check, it was only measuring around 6 fL. I immediately ordered a new lamp, hoping that would restore what I knew to be a very good picture.
A week later the lamp arrived, and after turning off the TV and waiting an hour for it to cool, as per the instructions, I popped it open and removed the old lamp.
I was shocked to discover that the glass stem inside the bulb, holding the filament, was actually pointed downward at about a 45 degree angle. It looks like it had partially melted near its base, and gravity took over. I can't believe it was still pumping out any light at all.
So I installed the new lamp, turned on the TV, and was amazed at how much brighter the picture was. Without changing any settings, I measured the luminance at 46 fL. I'll let the lamp settle in a bit before I really try to tweak it, but the picture is better than it ever was before.
So now I can't help but think that the original lamp was defective from the beginning, and just got worse over time. When the set was brand new, it never had such a bright display. I had been happy with it, because the colors were very good. But this is just a revelation.
I guess maybe I should have sprung for a pro calibration back when it was new. The calibrator probably could have told me right off the bat that something wasn't quite right. Oh well....
Anyway, a very simple lamp replacement procedure has now gotten me an essentially brand new 73" display with an amazing picture.