My sun roof is sticking. Help?

I own a 2001 Mitsubishi Eclipse and ever since I bought the car you need to push up on the sunroof to get it going. From what I heard this is common for the 3g's? I have tried WD-40 on the rails but it had little to no effect. Please help if you have any advice. I'm afraid that its going to break on me or something and that will depreciate its value when it comes to selling soon. Thanks