(I tried to edit my previous post rather than create another, but don't seem to be able to figure out how. I'm not meaning to rack up points here, I'm just trying to dd new information!)
So in the spirit of discovery, here's how I went about it. For the complete non-techie (like myself): there are 5 short black screws at the back (one is hidden under the filter flap) and three long ones in recesses underneath the projector; they are all marked with arrows and hold the top half of the plastic shell. The metal shielding under that is held via nine small silver screws and one black. I mentioned before that the metal piece seemed to be glued to a couple of IC chips; there is certainly some rubber padding that might be fused, but I managed to get the shield off no problem when the projector was warm
. A circuit board covers about 2/3 of the "guts" and ends around the inner edge of the lamp assembly (that we slide out the back when we change the bulb). Just inside of that, tucked under the edge of the circuit board, is the cinema filter mechanism.
The easiest way to find that is by identifying the switch that activates it, which has three black cables coming out of it. And if you sight along those you'll find a small hole in the metal cover where you can see the little finger that you can also see on the drawing. On my machine it's bright blue (you can't see it on the photos). The drawing is looking out from the center of the machine towards the fan side, my photos are taken from the rear and the right (the side with the main fans and the lamp housing).
I was able to fix the issue without removing anything else.
My aim was to set both HDMI inputs to "Living," which means with the filter out, because I need the brightness but I don't like "Dynamic" mode. However, by this point in the proceedings (one factory reset later) both were (re)set to "Natural", so any time there's a live source attached, the machine tries to move the filter in and gets stuck like Relik describes. I took a skinny screwdriver and pushed the top of the filter as far to the rear as possible ("in"). Then I turned on the projector and plugged in a live source. The manipulation was enough to get the filter unstuck and it slid into place. If you're okay with using any of the settings that use the filter "in", leave it alone and close up
, you're done! The factory reset makes sure all inputs are set to the same ("Natural") setting, so you shouldn't have any problems with the cinema filter engaging when switching inputs.
However, if like me you want it permanently "out", then you cross your fingers and switch to, say, "Living" mode. With any luck, the filter will slide out. On my machine, it only gets stuck in the other direction.... Which means I had to repeat the procedure on HDMI 2 (switch inputs; witness cine filter trying to slide in again to conform to default "Natural" setting; witness machine turn itself off and show 2 red warning lights; switch it off manually; let it cool down; push filter in; turn it on; change setting for HDMI 2 to "Living").
I also didn't disconnect the power to the cinema filter, because I wasn't sure whether than would cause an error. Instead, I just won't change my cinema setting ever again. With any luck, my Z3000 has a few more months or even a year of faithful service left. Thank you so much, Relik, for getting me started on this rescue mission!