560SL owners, air filter housing question

[domchang]

The picture is the top lid of the air filter housing. You can see the little opening to the right of the hold down screw, which is circled by a rubber washer-like seal, however the hole goes into the air filter housing and am wondering if something is supposed to be there mounted into this hole?

[Gilly]

The hole is there to allow access to the mixture adjustment tower with the air cleaner in place. The rubber ring seals the lid to the base of the air cleaner assembly.
Unsure about the filler panel picture.
Gilly

[domchang]

thanks very much, just wanted to make sure I was not missing a component, just got this car from a wholesaler down in TX and there's no maintenance history.