What is the tool for this called?

Doing some work on my boat and I have a spot light that tilts and spins. The light doesn't spin anymore because the brass nut in the picture was loose. I managed to get it out with some needle nose pliers, but doubt that I'll be able to get it tight enough when I put it back together.
A typical spanner wrench won't work as that sits in a void about an inch deep, so I figure something like a socket would work best.

Any ideas?
Thanks

 

Probably had some one-off tool to get that in. Could maybe use some 90 degree needle nose pliers?

Or these circlip-type ones: https://www.ebay.com/c/923217275

 

This isn't a one -of tool. The light was made be a company called Sparton.

My bet is they had something similar to a cable TV installers connector nut driver or hollow straight through for this flex cable to pass through. It needs to be thin walled as well. There isn't a lot of space...

If I had a lathe, this wouldn't even be a question.

 

Spanner wrench.

 

I've never seen one with tips as long as I need.
But yes, that was my first thought as well.

 

Just because it's made by a manufacturer doesn't mean they didn't have custom tooling made. It happens all the time.

However, something like these (https://www.mcmaster.com/wrenches/drivers-for-spring-plungers/) might work.

 

@buyobuyo I definitely agree with the custom tooling. I was hoping to not have to go the custom route though.
Such is life...

 

Get a piece of metal pipe and make a tool.

 

That's the plan. Although I was planning to donate a socket for this.

 

How will a socket work? Is the tube flexible enough to get a ratchet wrench on top of the socket after you cut the sides of the socket off? Sounds like a lot of work to make a socket fit.

I think it will be easier to get a small 3/8 wrench or whatever size fits, drill a small hole at the tip of each side on the open end. Make the hole just large enough for a metal dowel (even a part of a metal coat hangar will work). Then tap the dowel in the hole with about 1/8” protrusion.

Or just clean it up well and thread it in using a flat head screwdriver in the opening. That would probably get it tight enough.

 

The socket works by having it meet my good friend, Mr cutoff wheel. Make a few cuts so I have the fingers to tighten that nut. I also need the cable to slide through. Vice grips on the socket will let me tighten it up nicely.