I thought maybe your lens face was broken. You can fix this.
All you need is some polypropelyne (sp?) and a soldering iron.
Any broken black plastic parts from the bike you may have around will work. Fairing parts WON'T work, they're ABS.
I cut off a tab from a lens that had a broken face, but you could cut and bend a tab from scrap in the shape you need. Use the soldering iron to weld it onto the black plastic body of the lens. No need for adhesive.
Practise first on some scrap to get the feel for melt point etc.
Make sure and ventilate your work area well - strong fumes.
Some pics:
Link To Turn Sig Fix