How to fix the LED module?

Hi all

I've just bought myself my first flashlight - a 502B with a 5 mode R2 LED.

http://www.dealextreme.com/details.dx/sku.16179

However, during shipping, the lens has come unattached from the LED. The lens is around 8mm in diameter, and did sit on the actual LED. It seems to be plastic.

However, it has come off. It seems a bit dirty, and covered in a clear silicon like material.

I'm wondering how to stick it back. My options are:
- Contact adhesive
- RTV Silicon
- Superglue
Anything else you can suggest.

What is the correct way to fix on this lens?

Many thanks

Andrew

Here's what I found out:

https://www.candlepowerforums.com/threads/251476