I had the same problem with my 140 body, one body shop wanted to replace the gasket , the other mask around it. They did not do any headliner work, open the moon roof mask the opening and sandblast, sand, prime and paint.I elected to replace, the gasket it was $128, body shop cost $67. They did a good job of painting and had them do the roof, but they forgot how they got the gasket out, and threw away the old one. The gasket is not the same dimension all the way around and has corners molded in. It does just push into a groove in the top, well they screwed it up and then cut out a piece to make it fit. The moon would bid and stick. The owner was beside himself, and ordered another gasket. I had tried to adjust it by pulling out and discovered if you put it in properly you needed the inch they cut out. I asked them for the new gasket and installed it myself.
Start in the corners and work it into the recess all the way around, I used a wallpaper roller, gently to seat it. I would look at yours before pulling out, as I recall the thinner end is to the rear and the fussy side up. I would look for the joined parts, as a guide, there are two joints where they are joined at either side.

You can probably pull out the old gasket out of the groove where you are painting, and push it back!