Thanks for the Oil shroud gasket! Yes mine was missing and not listed in the parts manual.
You're welcome! It is listed in the book under the old part number of 122-0347. New number is a 122-0502. Description is "Seal, Air-Oil Filter. Very important as is prevents the cooling air escaping from around the filter to tin cover gap. If it's missing and you put your hand near the filter you can feel a lot of air coming out that is not cooling the cylinder on that side!
The cut out area needs to be at the "bottom" when installing.