Just for more thoughts, I had a significantly easier time taking the lens off my second headlight by cutting the flat lens part next to the channel with my dremel and then using a hot knife. The hot knife seemed to easily cut through the seal and cause resistance when i touched the channel.

But make sure you buy a good knife. I bought a $15 one on amazon that had two screw attached chucks for the blade. Both of the chucks bent after 20 minutes, probably since I was using force. It survived long enough to get the lens out with minimal damage to the channel, but it was $15 down the drain.