[Downwindtracker2]

I overheated the #7 gas lens cup and it broke. I'm a rookie. So off to the tool store where I bought the welder but they didn't have any #7, just a #8 and #6. I picked them up and a spare gas lens. So I went a little further to LWS and bought a couple of #7s. They didn't come up to the white plastic seal, they left a little gap. So I finished with the #8. The torch is a WP-26 that came with the machine. Chinese.

[Oscar]

I can only assume your question is: how do you get the cup to seal against the white insulator?

I'd start by disassembling the torch to make sure the gas lens collet body is threaded in fully into the torch first.

[tweake]

i take the 8's fit but the 7's don't. possible the 7's are either out of spec or a different series (assuming both the same brand).
different brands could simply be different.

got a pic of them and the brands?

[Downwindtracker2]

In both cases, there was no brand,a plastic bag on a wall rack and in the storeroom out back. I hate nonstandardized stuff . I take it , a gap matters .

[Car-Cray-Z]

Are you sure that you got the gas lens and cup for a WP26?
The gap definitely matters. It'll draft air in from the back side and contaminate your welds if it's not perfectly sealed up.