The o-ring looks kind of worn out?

It shouldn’t be but I’be taken the bowl off maybe 10 times with this one. Possibly the wrong o-ring I guess? I know I read someone the size of the o-ring you can pick up at a local hardware store. I should find that and just go buy a new one 

Looks like 007 metric 

Great clear pics thanks.
Is the piece you're using 'not extending far enough' for the Oring to fully enter the bowl cavity.
Is the brass washer there.
In one side on pic i thought the hex was slightly dissapearing--but in straight on pic i think i can see the brass washer, or am i just looking at the ende of the needle jet past the hex & no washer.
Washer is quite thick therefor adding length for the Oring to engage.
Should be able to feel deffinite drag on the Oring when fitting the bowl.
If you want to prove a point just work out a way to screw a main jet straght in to needle jet.
Or severely restrict the Oring holder with fuse wire but keep the needle in mind as not sure how far down it reaches.

I added pics that show the washer and then how much room there is with the washer installed. Good thinking though I hadn’t thought of that. I can feel the o ring hitting when installing the bowl. At least that’s what I think it us. 

As Mark said--The o-ring looks kind of worn out?
I expanded & saved that bit, hope it works.
photos.app.goo.gl/e5FNt6Jga4CLyUuF6
Keep the brass washer in mind too looking at the pic in link as hex is recessed & i might be wrong but i think usualy it is pretty much flush.
That, plus the Oring are both important as bowl has a taper lead in about equal to the brass washer thickness--by memory.

Weird. So do I have the wrong washer maybe 

Or could it be the holder is not pressed down far enough? 

Can we have a pic of the washer.
It's brass & about double thick compared to your average steel washer that would fit in there.
The important thing is that the Oring thing reaches far enough to compress.
Should be noticeably hard to push the bowl over it for the last guessing 4mm before reaching the gasket to screw home.
Definitely get a new Oring though.

Yes I will be getting a new o ring. Maybe the one I put in wasn’t the right material. If you go back and click on my pictures link I added pictures of the washes and what it looks like installed and without it.