S35 Cooke anamorphic i SF lens customization?

[Dominik Bauch]

In general I really like the Cooke Anamorphic i SF series. However I'd love to minimize / remove the slight blurring top and bottom of frame, most noticeable with the 50mm, 75mm & little bit 100mm lenses. So a subject is in sharp focus but becomes slightly blurred at the top and bottom of frame. 

I have zero knowledge of lens manufacturing and the elements used to make up a lens but it seems that this 'smearing' lessens as the T stop increases, also it seems to become less apparent when focusing to infinity. Is this blurring possibly an element that could be removed or replaced to lose this blur altogether?

Part 2: The 65mm Macro is pretty tight image circle wise, just a hair more would cover a couple of useful Alexa Mini LF modes. Is it possible to expand the image circle slightly?

Are there any LA based lens techs that could handle this safely and well?

Many thanks for any insight or help here.