It looks like there may have been a black gasket on that fitting--its so squashed it looks like part of it ?...
I'd leave out the paper gas filter & spring and install a universal gas filter in the steel line--then you'll never have to deal with that fuel line fitting again and risk stripping the threads or cracking the carb there..
Those OEM gas filters are worthless in my opinion--when they get clogged enough,the pressure builds up and the spring lets the filter move and gas to flow past it--along with any crud and dirt..then you risk destroying the carb trying to replace it..
Forgive me if I'm repeating myself..
I'd leave out the paper gas filter & spring and install a universal gas filter in the steel line--then you'll never have to deal with that fuel line fitting again and risk stripping the threads or cracking the carb there..
Those OEM gas filters are worthless in my opinion--when they get clogged enough,the pressure builds up and the spring lets the filter move and gas to flow past it--along with any crud and dirt..then you risk destroying the carb trying to replace it..
Forgive me if I'm repeating myself..

..luckily the rubber hose to the filter hadn't started burning yet--but would have,if I had just went in the house and hadn't noticed the flames!..(good thing it was diesel fuel,not gas ,too!)..
..nice to know your computer is just another "snitch" ..
..sometimes I feel that is the main reason for the internet--to spy on people,and use their own words against them..