My W201 roof acted like that for a short while, now it does nothing. It seems that the mechanism that raises the back of the roof has broken and is jamming the roof. The FSM says that the roof must be partially opened to remove it, and I cannot open my roof at all so I am in a bit of a quandary. I've managed to slip the interior trim back and I think I can remove some of the hardware that will allow me to take the roof panel out, but I'm waiting 'till the weather is consistently warm to fool with it some more. Perhaps your roof is on its way to a similar fate?

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1987 W201 190D