I invite your attention to the moveable panel that crosses the car immediately behind the roll bar ... it's what we'd call the "sundeck" on non-convertible cars. Mercedes has a technical term for it, no doubt, but I do not know that term. It raises and lowers when the roof mechanism is cycled.

The panel is covered with a leather-grained vinyl sheet that is (apparently) glued to the panel surface; the sheet wraps over the edges of the panel and is glued to the panel's bottom side.

On my R230, the vinyl cover has come unglued in one section on the leading edge of the sundeck panel. I noticed the edge of the sheet was unglued when I raised the roll bar over the weekend. When the roof open/close switch is cycled, the sundeck panel is one of the first to open. If I stop the open/close cycle with the panel opened, I can easily tuck the unglued covering back into its proper position ... but it won't stay there. It has to be re-glued. I cannot re-glue the covering with the panel closed: the panel edge is too close to its mating surface for me to apply adhesive to the loose flap and work it back into position.

Two questions:

1. What type or name brand adhesive is proper for re-gluing the vinyl cover to the sundeck lid? Super weatherstrip adhesive comes to mind ... but that's just a guess. What do you recommend? Is there a Mercedes-specific adhesive for this job?

2. I need to raise the roof out of the trunk just enough for the sundeck flap to cycle to its open position, then I need the flap to remain open long enough to apply adhesive, position the flap, and allow the adhesive to cure. With the engine idling, how long can I safely leave the top slightly raised while I work on the sundeck? Or, can I safely place an object--maybe a low-seat shop stool with a raisable seat--under the back edge of the partially-opened roof and allow the roof to settle onto the object instead of just lowering completely into the stow position, or would that throw Earth out of its orbit, cause Russia to march into Ukraine, or spread the Zika virus?

 

I would use something like Gorilla glue sparingly and clamp the edge with something like a plastic clip used to close potato-chip bags. Then leave the top partially open, shut off the engine and leave it. I doubt the roof will sink much while the glue sets. You could always temporarily use a strip of plastic trim molding and if the top settles, it won't hurt anything. As far as the consequences, most of those have already happened

 

I would use a contact adhesive. I have actually had very good luck with "Shoe Goo". Get the waterproof boot-and-glove formula. I recovered the sunroof shade in my C240 with a vinyl fabric. I tried all sorts of adhesives, but the Show Goo has held fast in the heat for a few years now. I like office supply binder clips for holding stuff like this.

 

OK ... I'll answer my own question.

The question is: what is a proper way to reattach (reglue) a portion of the vinyl covering that has pulled away from the edge of the "sundeck" flap on the Vario Roof unit.

Tools (such as they are):
1. Permatex Super Weather Strip Adhesive
2. Acid brush (get a bag of 'em cheap at Harbor Freight)
3. Office Depot's Report Covers with Sliding Bars ... those clear plastic document covers you used for school reports and papers, with the slide-on compression bar, or strip, that clamps everything together.
4. Popsicle stick ... for spreading open the compression bar

Steps:
1. With Vario Roof in full-open position (top stowed in trunk) and engine idling, cycle the roof-close switch to the point that the sundeck raises from its horizontal stow position to its vertical position. Release the roof-close switch in mid-operation to hold sundeck vertically. Leave the engine idling so you have time to do your work; you may have to cycle the open/close switch just a bump after 10-minutes or so--otherwise, the top starts settling closed.
2. Place a towel or large rag beneath the sundeck panel; this prevents adhesive dropping onto places it isn't wanted.
3. Spread a glob of Permatex adhesive on the acid brush and apply the adhesive evenly to the exposed vinyl covering; spread another application to the hard plastic sundeck lid where the vinyl is to be reattached.
4. Allow the adhesive to dry for 10-15 minutes.
5. Spread one end of the compression strip open (with the popsicle stick) so you can start working it into place.
6. Fold the vinyl strip onto the sundeck plate and quickly slide the compression strip over the folded vinyl strip so that the glue on the strip meets the glue on the plate. The two surfaces mate instantly; you can't slide them around for better positioning once they meet.
7. Return Vario Roof to fully open (if it's in the garage) or fully closed position and allow time for the adhesive to cure fully. I let mine dry overnight.
8. Cycle the Vario Roof switch so that the sundeck flap opens up; slide off the compression strip, being careful to ensure that there no adhesive sticking the strip to the vinyl.

You're good to go. Something else may come undone over time, but I'm confident that this bit of vinyl covering is forever in place.