Specifically, a Night Enforcer 260? (at least that is what I think it is)

Symptom: Push power button, tube lights up, red light flashes quickly, device shuts down in 5-10 seconds. Push power button again, problem repeats. Tube works perfectly fine while on. Great image.

My understanding is that this model has a bright light shut off feature, and I think the photo cell might be dead. I have never taken one of these apart, so this will be a new adventure. The objective is motorized focus, and this unit has manual gain. The image tube is actually quite good and clear.

Any tips on disassembly?
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From a google image search looks like there is 4 screws on the bottom. My bet it is its glued too, but a thin blade should be able to split that after the screws are out.

Becareful thou sometimes things like the objective and ocular are also glued on.

EDIT.

Also I doubt the photocell is dead, normally the opposite would happen, if it dies it wont shut down in bright light. There is circuit that when it senses a light it starts a "timer" so it shuts down if the does not go away. There is photo resistors that allow power to flow or not allow it to flow when exposed to light.

Its is most likely a photo resistor, and yes that could go bad and cause the issue. Easiest way to test is find the photo resistor and put an ohm meter and it and shine a light in to it. If it is a photo resistor you maybe able to replace it witha 100k ohm resistor and disable the shut down circuit

https://en.wikipedia.org/wiki/Photoresistor

That's the part I was referring to. The photocell resistor, sorry.

I repaired this unit. It was indeed the photocell resistor that was faulty. I clipped the wires on it and the unit fired up perfectly fine. I am going to just keep that circuit disabled for now, but i may end up replacing the resistor, because it is pretty easy to turn these on without realizing it.

If this helps anyone else - here are the insides.
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looks like it was glued, be careful on what you glue it with. silicone's and a few other "glues" have a large percentage of acetic acid, which will wreak printed circuit boards.

What kind of tube does it have?

you can see the tube inside of it, when cracked open. it will not fit anything else, if that is your plan. i am not sure as to the exact format/type

This unit was also difficult to work on. The entire thing is GLUED together and screwed together and then sealed shut on top of the GLUE with some type of RTV like sealant.

Thanks for the note on being proprietary.  There is the marine version on eBay now (night mariner) that has the same problem as your did. If it took a standard tube I probably would have tried gutting it.  But it's only a few 2 anyway.

I thought I've seen some of the itt commercial units with mil style tubes on them