Hi,Welcome to Just Answer, My name isXXXXX will be helping you with your appliance issue today.
do you have a model #?
ok, its called the lamp cover. you can get this at the following link.
http://www.searspartsdirect.com/partsdirect/part-number/Sharp-Parts/Microwave-Parts/PCOVPB047MRP0/0022/575/Model-R1875/0958/0123370?keySuffixId=&productTypeId=&searchModelNumber=R-1875&blt=06&subCompDesc=OVEN/CABINET its only $5.49 and you should replace it, thanks , Bryan
OK - so the part has arrived - it is --of course-- not the correct one (haha) and not returnable. I am now debating whether part # 04-43 is the sticker-like option I need to cover the light open/perforations?