I'm also looking for the polarizer and filter to rebuild the light engine on my JVC 70A478, an early 2008 70" model. The picture is getting very dim, and I would suspect that if the polarizer isn't working properly, then the light isn't getting through the light engine properly. I can't find a rebuilt optical block, and I don't like the idea of throwing out a $5k TV after 4 years.
I did take it all apart and clean off a light brown dust from everything, including the lense. There was enough dust on the lens that I thought it would make a difference, but I really can't tell much from before and after.
I found my service manual here:
My HDILA light engine, optical unit, optical block, is the COP11A-SSA
Here's some technical info on the JVC that I found that you may find interesting, this is where I see the description of the polarizer and the filter.
I would appreciate any information on parts source for the polarizer and filter.