Hi there Tom
I did exactly the same as you with both sun roofs, only what you may not realise is that it still might be leaking but you don't know, I took the bottom frame out, done both the plastic drains, took them out and resealed them, tested them and no leaks, until it rained, had another look and turns out it's the seal on the tray this time, so mast iced all around both sunroofs, I still get condensation in between the roof lining and roof, this is because you can not get every bit around the tray, so get a little drip every now and then, the only way to do the job properly ( which I'm going to do in the summer) is take off the trays again clean both surfaces and cover the the tray in mastic to make a proper seal, hope the helps