YOu can't order those seals, you can't order most any body part for these cars. If the seal is bad, you've got to fo find a junked roadster somewhere and get the part off it. But here is my advice: It is up to YOU to take a GOOD LOOK and determine what is wrong. (Or take it to any DIY person who is observant and somewhat "mechanical" and pay them to look at it.)
MANY of us have dealt with this: You are not seating the seal correctly.
Mine was fine, then we replaced the top. Right away, it kept popping out. It took me maybe five tries over three months before I finally got it to sit in there and stay. I got sick of what has to be something simple, and finally reseated the damn thing in the following position, where I could tell how it was seated, then watched it as the top went thru the cycle to see when it was popping out and what was causing it. I can't remember, it was over two years ago, but I saw how I had it positioned incorrectly and reseated it.
It's been fine ever since.
YOu seat it with the top in this position and then cycle the top and watch what is happening, that's all I can remember: