Re the higher air filter cover.
I had 2 x 076 supers and 1 x 076 av and all had the same low filter cover with the three small cut out slots on the bottom (although obviously the supers sat higher due to the extra intake spacer).
I bought another 076av sight unseen and when I got it the filter cover was damaged so I bought a new one from my stihl dealer, when it arrived it was the high top one with no cut out slots.
It fits, its just higher, so my guess is that the high cover was simply an "improvement " which superseded the low cover. However like I said this is simply a guess i haven't tried to verify it.
I had 2 x 076 supers and 1 x 076 av and all had the same low filter cover with the three small cut out slots on the bottom (although obviously the supers sat higher due to the extra intake spacer).
I bought another 076av sight unseen and when I got it the filter cover was damaged so I bought a new one from my stihl dealer, when it arrived it was the high top one with no cut out slots.
It fits, its just higher, so my guess is that the high cover was simply an "improvement " which superseded the low cover. However like I said this is simply a guess i haven't tried to verify it.