I decided to open them in the end mate, bloody tough job still trying to prize it open. I’ve purchased some of that butyl rubber sealant... do I just use that mate or black silicone aswell?
Yeah they are not the easiest to open but slow and careful is the best way. Just the butyl, I always scrape out all the old stuff from the housing and off the lens before putting new in. This way you get a perfect seal