Apparently the adhesive on the clips that holds the headliner up has reached its "expiration date!" First one, and a week later, all of the clips came unglued. Does anyone have recommendations about what kind of adhesive to use on these? I tested an all purpose hot glue, but that didn't work. Appreciate your input. Thanks 😄

 

This is apparently the fate of every C70 convertible headliner. Mine as well {2009). I've spent tons of money having the pros fix it and tried myself. I've read of people spending in excess of $6000 to fix this issue and they all fail within a very short timeframe.
My efforts failed also. I think I tried every adhesive known to man and many, many hours fixing it over and over. Not even mentioning the stress it puts on the top being stopped in mid retract to do the work. Forget adhesives. The best one lasted me about 5 weeks and down came the headliner. I had enough.
My solution is something many may not be able to bring themselves to do, and I expect many will cringe at the thought, but it's a permanent fix. I haven't had any problems with it for almost 4 years now.
What I did was very carefully take out every retaining clips (that the adhesive is on), be very careful because they are brittle and prone to breaking and you'll have to find new ones or compatible alternatives, drill a very small hole in the center of the clips. Replace the clips back into the roof. Buy an equal number of small, short screws and washers. Again, take care as the headliner will be hanging loose. I started at the outer edges of the headliner so it stays taught, driving the screws with the small washer through the headliner, into the small hole I drilled into the clips previously. To cover the screws I purchased small round peel and stick felt pads and placed them over the screws. I was lucky enough to find the felt pads in the same color as my headliner. Everyone thinks that it was made that way and it does look good.
This solution was the permanent fix I was looking for and I think it cost me around $18 to $25 and about 3½ hours work.
Good luck on your headliner fixing journey.