Ahh....the 240 sunroof.
Have you tried to "help" it
Open? While turning the crank
Use your other hand to give assistance and push the sun roof at the same time....this technique is also helpful while closing her too.
But, be ready to take her apart once it is open, because she may not want to close after getting her open. It is not rocket science, but it is time consuming. If having to remove her completely she lifts out with rails attached after ALL screws and winding wire/rod tracks are removed. Do not lose any screws and take pictures along the way. Good luck. I've taken mine out a few times for maintainance and fixing. Have a flashlight handy to look into the space between the roof and headliner. Might as well have a long wire, like hanger wire but a little longer, ready to clean out the water channels while you have her apart. One canal in each corner (flashlight is helpful here). The front two drain out near front door hindges and the rear two go through the trunk area and drain behind the rear wheels. And again good luck. Have at least an afternoon free and a garage available if it might rain. Don't ask me how I know.