tintop sunroof problem

i am refitting my sunroof after overhauling it and painting etc to my 83gti which I removed 10 years ago when I started restoring it.
problem is it goes very stiff when closing , can anyone offer advice on adjusting
 

Have you sprayed some silicone spray on all the runners? That made a big difference to mine. Also have you used a genuine vw seal? as I've heard that the non genuine ones don't fit very good so could be your problem if thats what you've used?