Ok I've just cleaned the LCD and the lenses and shot some pics that might help you out.
Some general suggestions:
1) I don't know if this can harm your eyes. I guess if you want to use the headset for prolonged time, then you should not do this. Then again, I never heard anyone complaining using google cardboard and a LCD phone (which this basically is) and none of them have the filter.
2) You will void your guarantee
3) Make sure you disconnect the headset !! If it's connected while it's open, then the firmware will detect it and will disable your device. If this happens, send me a PM, I have a hack to get you back online
4) A few different screw types are used, I suggest to keep them separated and label them so you know which screws went where.
First I suggest to use this video as the basis on how to open the PIMAX, it shows the screw locations and everything: https://www.youtube.com/watch?v=Cn4OvxV7XpM
1) Remove head strap
2) Pull off the foam
3) Remove front cover like in the video (just 2 screws)
4) Remove the rubber layer like in the video (couple of screws)
5) Now you will be left with this:
There are 4 screws that keep everything together. Also if you assemble it again, first put those two plastic parts together and then insert the core part with the LCD screen from the back and screw them together again with those 4 screws.
6) Now the core part can be taken out:
7) You can remove the lenses with the 3 screws each, but you don't need to. You need to remove the whole upper part from the lower part. You can see in this photo where the screws were that you need to remove in order to open it up:
(in the above photo, I've already taken out the filters)
8) The filters are connected with cables to the mainboard and they look like the last photo of this post. On the connector they've put some black tape to keep it from making contact with the mainboard. Remove the black tape. After that you can slowly and gently pull out the cables. Put some new tape on top to make sure again that it doesn't make contact with the mainboard. In this photo you can see the green tape I've used:
9) Clean the LCD and the lenses carefully. If you leave even a tiny bit of dust, you will see it later on and it will disturb you. So take your time to clean them well.
10) Now you assemble everything again in reverse order. Take your time. Make sure the cables aren't getting stuck and that the LCD cable didn't get disconnected (you can connect it again if it did, it's quite easy, just push it on softly and after it clicks put on a bit more pressure to make sure it really connects). There's also another mainboard data cable that might have gotten disconnected, check it all.
That's it ! As you can see on how black the filter is: you can imagine how much the screen improves after you've taken them out It really feels like a whole new headset ! No more dull screen, but crispy and clear like it should be ! I personally feel the whole VR experience comes much more alive without those filters.
Last note: I'm now running with brightness set to low_level_1, so that's 1 level below 'normal'. But I guess normal works fine too. Just don't use anything higher than normal. See the brightness topic for the codes to change the brightness.