There is a long stretch of thin aluminum running down the side of the lid,.. that's what broke out when I didn't shave the nubs enough.
I used to just snip them instead of razoring them close.
After that I switched to the flimsy lid seal and had problems with it staying in place while I lined up the LDA lever and idle RPM bump lever,
pinched one and it leaked so I went back to the shaped seal and started trimming with the razor blade.