Those plates are about $7 at O'rielly's or autozone IIRC.

They tend to get "lost"...

That 1" spacer may do the same, however, it introduces other potential issues. Get that plate #2732 and try again.

Reset the carb idle mix screws to 1.5 turns out. If you get the plate on, the idle should increase a bunch because your leak should be gone.