Fuselage tank overflow elbow missing...

I found the drawing for the ternplate tank, if that is what you have. It shows a riser on both the inlet and overflow
www.ercoupe.info/uploads/Main/drawings/a-602.jpg

I'd appreciate the picture if you could send me one.

I am aware of the header tank not getting 100% full but because of not having that elbow my header tanks level do not reach the heights where it should be when it is considered full before the overflow process begins.
Because of that height difference inside the tank my tank's full capacity is lower than 6 gallons and I am assuming the difference is about 2 gallons or so...
Without that elbow 6 gallon tank turns into a 4 or 4,5 gal tank as in my case.

If there was ever an elbow where it supposed to be I don't know how it could've been unscrew itself from that inlet and fell out but I'll still check it out inside the tank..
And again, thank you for your response!

You can drain your header tank and look inside with a mirror, you should see a aluminum tube from the aft wall of the tank, the tube will have about a 1in joggle in it, that puts the end 1 inch ABOVE the fuel inlet, The header tank never gets completely full, as far as the float setting, measure from the filler neck to the fuel and then compare the measurements to your float. If you need it, I have several header tanks I can try to get a photo of the tube using my borescope.

I'm sure it's possible. I imagine you will have to borrow a bunch of tools and a boroscope from your local laparoscopy surgeon.

I've an issue since I bought my 1946 415-C's Header tank fuel gauge. The bobbing stick is almost slightly over halfway of the glass tube when I know fuel pump is working and there's enough fuel there.

At level flight for over an hr that bobbling stick stays at the same level because I always have fuel in my wing tanks and pump feeds the fuselage tank as it should...

But lately I realized that the even at full capacity my fuel level in the fuselage tank is still a little low due to the overflow elbow supposed to be attached to the back wall and coming upward towards the filler hole of the fuel tank is not there.
Instead there is the hole on that wall of the tank with screw threads inside for that elbow supposed to be attached.
So my overflow begins to happening before fuel level gets a little more higher than it currently could due to that missing elbow.

I have no idea if there was ever an elbow there or not or if there was one and something happened and fell inside the tank or not? If that's the case what's the best way to fish it out there?

Also since I can see where the elbow supposed to be attached but missing, is it possible to attach a new elbow to those threads somehow easily without disassembling the whole tank and without getting a second mortgage on the house????
I mean is it possible to do that thru the filler hole???
Please help!