My Koups brake lights had a leak. It was the rubber seal. Yrs of dust, dirty & deterioration weakened the seal. I just cut out circles of Flex seal tape & done.

The dime sized rubber foam seals & housing foam seals deteriorated, I used as emergency seal. Duct tape window seal. Has been raining frequently. The green circled area was also the area the foam seal was no good. I took a strand of the Duct tape seal to make my own seal. When done with diy seal, I pushed them into their spots causing the maliable seal to conform, squish & create the seal at each 10mm screw.

 

While fixing the seals & oven was already in use. I resurfaced the "new to me" brake lights lens back to new, 2k Spray Max clear coat & baked in oven.

 

Yes, baked or heated headlights (SOME brake lights) will allow one to the insides.

There's different oven baking temps on the interwebs. The higher the temp the more watch like a hawk is demanded.

Higher temps can also warp, melt & ruin.

As for me, I set the oven temp at 175° safe & hot enough to leave unattended (restroom break, family needed me, a side quest needed doing) for about 10 to 15 min without worrying of melting or warping.

When the headlight is heated for about 20min at 170° to 180° wear thick gloves/gloves to handle the hot plastic & with a flathead screwdriver, a plastic panel clip remover or non serrated knife (butter knife) start at the open/blunt end of the headlight & work your way to the pinched/corner & pull apart & upwards.

I'll post what I used to make it easy. Running errands.

 

These are what I used to get the opening started at the widest/blunt area of the headlights & working my way down as I opened/pulled apart at to the pinched/tight area.