I think it was "Goof Off" that I used on Lexan and it did craze the
material. Get a spare piece and try it out first. Crazing a canopy or
windshield youself is something that grown men cry about.

After I crazed the material, I got a 3 part plastic refinishing system from
Sears and eventually polished it all up.

I have small sheets of old acylic with the brown paper still on after about
15 years. So, it does not want to come off. In my case, I put in in the
sink with warm water and detergent and it eventually comes off. So, I
suspect the soap suggested by Denny is probably the best solution.

Naptha may also work. As I recall, the ingredients are not published, but
it may not be petroleum based. It is a great cleaner for camera shutters.

Colin