[MikeS100]

The windows should drop a couple of inches when you push the button down, and then the next step is for the rear window section to lift up. It sounds like the operation is starting ok but then getting stuck at that point. There are a lot of microswitches in the system so I wonder if one of those has failed. If the microswitch isn't working then the car may not be able to tell if the rear window is latched down or not, so it might be stopping the operation to prevent damage. On the other hand, it could be that the roof control module is faulty and isn't picking up the signal properly so the module is stopping the operation.

To be honest, with the symptoms you have I think it's going to be really difficult to try and work out where the fault is without a proper diagnostic. Otherwise you might end up just replacing parts in the hope that you're replacing the faulty bit.

Cayman autos in Surrey might be worth a call, they are convertible specialists and seem to know their stuff. They have dealer level equipment so should be able to diagnose. If you do decide to go there negotiate on the price though, they wanted £120 for a roof calibration but dropped to £60 without any trouble at all. Bit of a trek from where you are but not too bad and worth it if you get an answer. It's not a bad run down, the company I work for has an office in Stratford Upon Avon as well so I have to run up there from Kent sometimes and it's an ok trip.