Removing headlight lens?

Does anyone know if this can be done on the 821 / 939 headlight? I have a broken tab on my headlight that is making it hard to aim. I found a replacement on ebay that has some rash on the lower left edge. It's otherwise functional and the rash is minor, but, given the lens on my headlight is perfect I'm wondering if I'd be able to easily swap them. Does anyone know? Worst case I suppose I can live with the rash to at least have a useable light at night.

Ah ok, I've read about the process of baking in the oven to release the glue. I guess the question now is whether it's worth the additional price to get a clean one. Found a different one on eBay without any issues but it's about $100. I suppose my time an frustration is probably worth the extra money.