Making a "stop" like you remember doing with a circlip would work too RT325...  the o-ring groove might possibly work to retain the clip and is a genius idea.

The whole point is something needs to be in place to keep the short slide from coming up past the guide pin or have the needle come out of the needle jet...  either of which would likely end in a stuck throttle and potential disaster.

Yep be careful. The Oring was up in the tall cap so it sealed on the first unthreaded bit when screwed home. Just be careful in all directions. I'll check partzilla to see if I'm talking rubbish again lol.

Yep number 24 looking at a "76 250 or 400 carb. All good.