Here are some more photos of the damage to the polarisers. 2 of the 3 had severe lines up it like the images show. One was sort of OK.

My best guess is that this damage is caused by particles of dust being blown up across the polariser, eventually digging into and damaging the surface

The polariser is glued in as part of it being aligned in the factory. In terms of getting a replacement you would likely have to get all 3 LCDs + Polarisers pre assembled and calibrated to replace this part.