Primus 96 damaged, need ideas to fix it

Hello again, the stove is now, and after multiple attempts in gently cleaning the orifice of the lipstick burner, functioning well and producing a nice blue flame. Two observations were made:
-Is there supposed to be a ring at the bottom of the burner where the thread connects to the tank? My stove does not have a ring.
-The second observation is a leak at the filling cap level, and even after trying different caps, the issue remains. It appears that soldering may be necessary, which I am not keen on doing for this item (I feel uncertain because the solder will look unattractive), and since the stove's flame is entirely blue, it makes me want to burn it, creating a dilemma.

Thanks all

 

Should be a lead washer where the burner screws into the fount. I've had to reflow or add solder to the bung for the fuel filler hole.
Duane

 

Take a photo of the filler cap area from both sides

 

This is to show these pictures.
The stove is working well now. Thank you very much everyone.

Regards,
Migwar

 

Good work getting it going. Now for some coffee.

 

Indeed. A good coffee was made.