Very embarassing question

I'm sorry, ignore the spring, it's actually off, it's a misleading picture. The spring is actually laying loose it's not attached to the linkage right now. It was attached to the other end.

Maybe if I use some WD-40 the linkage can slip off the insulator ?

You will likely break the old insulator removing it. They get hard with age and break when you remove the linkage. I just take a flat blade screwdriver and pry it out.

What I find interesting is the placement of your throttle return spring. It's pulling the throttle open instead of closed.