Hello - I have a pair of flak jackets on order and they seem to be a style with replaceable lenses. I've had a few pairs of oakleys in the past but I've never tried to replace the lenses. I may need to replace the lenses on my flak jackets with a different lense style after I get them. Can you recommend online instructions or video that shows the proper way to replace the lenses on flak jackets? I want to avoid damaging the frames or the lenses.