wow does this mean im some kind off recognised authority on open airs?
I wish!
Though i do ahs some info to offer i guess. My rooof never used to open at first, it seized up in two ways. One was the Cog in the motor had knackered itself and the other being the roof had sorta how does one sday... crusted to its runners!
To get to your motor and take it out could not be simplier. You have to first remove the motor housing/dash light thing. My terminoligy here is obviously bad so an i.e: the thing with a light and a switch on in the middle of the roof. To remove this you slide it towards yourself (i think!) and then pull the more forwardly end down. if you want that out of the way unplug it and chuck it too one side. The motor )again if memory serves) just comes out with they removing off a few screws. From there i would give it a quick common sense diagnostic. Like pressing the button to make the roof retract while the motor is connected elctronically but not physically, i.e after youve taken the screw out and have it dangling.
If the mechanism is turning then obviously the motor is fine and you have a problem with your roof seizing. The way i sorted that problem was magic. basically my mates dad done it while i wasnt there so i couldnt personally tell you im afraid!
if its the motor then your best bet is asking down your local VW. If you when you press the button and you hear the motor truning but the mechanism doesnt seem to revolve then i suggest you open it up and make sure the cogs are in-line> this was the problem i had, i thuink i had to stick a washer or two behind a cog to re-align the mechanism so that it would function properly.
Now ive re-read the opening post it sounds like you might have to open the motor up if its definately running. failing this my only suggestion is see VW about it.
I hope you get it fixed, nothign beats the experience of a semi-convertible! Except maybe a ferrari or cutting grass...
Meph.