I see you now know what I was talking about when you picked up the transmission from me
It is a screen and not a filter. The only way to remove it to clean or replace it, is to remove the valve body.
When I went to replace it about a year ago (Not knowing then, what I do now), I took out all the bolts. When I went to bolt the new screen up, the one bolt would not thread in. I then realized I was SCREWED. After a quick look in the FSM I realized that the nut and washer were sitting on top.
So, I ended up removing the valve body and reinstalling the screen.
So, don't worry about it, because you are using my old valve body and the screen is fairly new. Plus, I did 2 flushes since then with the AMSOIL synthetic.
After discussing my fustration w/ a local Nissan mechanic, I now know the CORRECT way to keep a Nissan transmission healthy for a long time. Here is what he told me:
1)DO not change the screen. (His reasoning was that just removing and replacing the valve body HIGHLY increases your chances of dirt getting in the valve body and doing damage or damaging the valve body from other methods.)
2)Do a COMPLETE fluid flush every 30K miles.
3)Use synthetic ATF.
He said if you follow those directions, your screen should never need cleaning or replacement and the trans should last 2-300K miles fairly easily.
I followed 2) and 3) and my trans had over 150K on it when I pulled it for the swap and still was working good.