[Collins] re: R-388 MC drum

[wli]

I am refurbishing my new treasure: a 1954 R-388/URR. The MC drum is severely yellowed on Band 1 where it was evidently left in repeated sunlight. The rest of the drum is intact, and only mildy yellowed. Is there anything else other than dilute sodium hydroxide that will remove the dark yellow band wihtout distubing the numerals?

Afterwards, I was planning to cover the entire drum face with clear acrylic in order to preserve it. Will that damage the numerals? 

Thanks

W. Li