Ah so you found the cause then i guess.
The grab handles have a bit of a knack to them. There are covers on the ends of the grab handles that expose the screws/bolts. They just lever off, but you have to be careful so as not to mark the headliner. they are the bits that run around the edge of the ends of the handles. Once you see how to pop them off you'll see the fixings.
There should be bolts holding them in or screws, and there are kind of pointed plastic studs aswell. Once the bolts are removed you just pull the handles off firmly.
There are more of those plastic pop studs elsewhere on the headliner. they do just pop out. Then the headliner is kind of hooked up at the rear. Its hooked up underneath the velour draught strips too.
And on each side, where you see a kind of seam on the headliner, just above the doors and near the grab handles - along that seam underneath is attached a piece of coathanger like wire/rod that hooks up to create the tension needed.
You'll also need to take out the B pillar covers. Two screws at the bottom of those to remove the bottom plastic cover. Then the B pillar trim piece should be able to be released downwards.
The sunroof trim around the edges needs to come off too. And the headliner is hooked around the edge underneath those in a similar way to how it is at the tops of the doors under the velour.
You'll need to get the A pillar covers off too. Those just unclip but it works better with a plastic wedge. I cant remember which direction they come off though. Towards you when sat in the car i think.. I think theres more plastic pop studs under there too to release the headlining.
The sunvisors have to come off completely, the rearview mirror (That just pulls off, its springloaded but be careful not to pull the bracket for it off too!) and all brackets on that ceiling panel at the front so it can be released down once the A pillar covers are off.
On mine it seemed to be glued at the front by the windscreen so i didnt pull it down completely. I just released the rear edge of it. I think i left the domelamp assembly in place. It was enough to get to the headliner fixings at the front.
All in all its a bit of a faff, but i ended up being quite impressed by how well it went back up, once i'd figured it out..
I wonder if you'll find rust on the metal outlets for the sunroof cartridge drains. if so, perhaps fibreglass would be an idea to repair. Otherwise you would need to swap out the whole sunroof cartridge with one thats not rusted.
Fibreglass might be okay, if you were to use rust stabilizer on it first. I caught mine just in time so i used Jenolite rust remover and slapped load of Hammerite on them.
Maybe, it will be just the rubber tubes that have perished, dont know where you'd get them but that'd be easier to sort out wouldnt it.
Good luck!
