Originally Posted by ZURCALED12
Do I need to clean off the old butyl rubber and apply the new one? it appears to me that I can seal it by baking it again or just applying the heat gun.
I clean it off 1 time for every two times I open a headlight (unless you see a trouble spot that may need some help). So this time it should be fine but if you open it another time I would scrape as much out as possible and apply new.
For putting it back together - press it together as much as possible and put the screws in. Bake at the same temperature you did to take it apart for 5-8 minutes, take it out and then tighten down the screws and press the light together any additional amount you are able to (shouldn't be much if any).