Today I was pulling up to the garden centre to find some furniture and maybe a good BBQ. It was a decent day in Dublin, so I had the sunroof open. I tried to close it, but it only half closed and then backed up a couple of inches. This persisted over several attempts. It was 2pm, so I thought I would get it to the garage to get sorted before it got too late. At 4, I rang to check the progress and they had just started to look at it. They rang just before 5 to say they couldn't do anything and were way too busy and asked if I could bring it in another day. I was disappointed to say the least, considering all the business I have given them.
I got the car home and removed the sunroof to get a better look at the action of the rails. It was clear that a piece of plastic was jamming the rail. I don't know why, as this piece was part of the guide. I removed it by tapping it out with a flat head screw driver and did the same on the other side. Success. It tool less that 15 minutes and the problem was solved. I had the opportunity to treat the rust on the inside of the sunroof around the glass, which was good. I am relieved I fixed it, but at the same time, I am annoyed the mechanic couldn't and I wonder if he actually tried.
If this ever happens to anyone else, the plastic pieces where my rail was jamming in about 3 fifths of the way to ward the windscreen. If the metal part of the rail is stopping at this part and then reversing back, you only have to snap the plastic piece out and the window functions perfectly after.