I’m not sure about that - just my meaning.
(However I’ve tried already to ask a contact in Taiwan, maybe they can reach Sturmey.)
I do know that the official repairs way is the same at ATS and Sturmey Archer; they want the defective drives back to refurbish them in house.
Good idea with the glass plate, also I think that there are not that many sizes available and there must be recognizable, certain steps between the sizes.