We notices a wet bathroom carpet on a recent trip. We removed the carpet to dry it out and found that, following a return journey through torrential rain, the floor was wet again. The rooflight was leaking.
On the first dry day I had a proper look. I removed the inside trim which only had 2 screws in place, then removed the inner and outer cover from the top. The sealed trim was now exposed and I gently pried it off using a wallpaper scraper. It took a while to get moving but suddenly went on one side and then the other sides gave way too. The sealant was more than I expected and included the normal grey mastic but some black sticky stuff too. It took a good hour to give the frame a clean and meths helped soften the gunge. The roof was an easy clean using meths. I gave all the plastic parts a good scrub in soapy water which should improve dramatically the amount of light getting in.
Plenty of sealant – a grey mastic I have used before on the rear window – and reassemble. I struggled to get the last two screws to bite on the inside frame. Puzzling. Whist I was on the roof, I resealed the Trauma heater chimney, which was getting very over grown with moss!
No pictures at the moment. Will add later