Sunroof issues

I've got a 98 gtp and the sunroof quit working. When you pushed the button it just made a clicking noise. I took the light pod on the roof apart and found a round red plastic piece had come out of what I assume is the sunroof motor. I put the plastic piece back in, pushed until it clicked into place and the sunroof started working again. Well a couple days later I am closing the sunroof and it stops working. That piece had fallen out again. I've "fixed" it three times now but it always falls out a few days later. Does anyone know what might be causing this or how to fix it? The piece rotate so I don't know that I could glue it into place, not that that would be a good idea anyways