I don't think that you can take out the liner without opening the sunroof because on my car the liner is sealed between the two layers of the roof. In your case i would try what the others have done and just push the button to open it and then try to force the roof to engage and sort of help it along. If you have a problem with that little clip then you should be able to get it started because that clip is supposed to connect the roof to the cable so you might be able to get the clip to catch it just enough to get the roof started.

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Pete

1986 Euro Black Metallic 190E 2.3 16V