Hanging skies ..

Hanging skies ..
... are like low clouds. It makes you gloomy.

For most of today's younger classics and you-timers, the Secret of The Hanging Hemeltjes is in the fact that the thin, flexible textile layer that now strokes your crown was once provided with a thin foam layer. That gave him body. And muffled some noise too. The plasticizer from that stuff has gone and with that the bond with the substrate has been broken.
The problem with re-gluing is often that the fragile textile has not been stripped of all foam residues, and will hang again after gluing.
Gluing can actually be done well by applying the glue in spray form (compressor or spray can). However, the choice of glue can lead to quite different results. And certainly if the glue 'hits' through the textile, then all the trouble was for nothing. 08080 car glue from 3M seems to give good results. When bonding with any glue, pay attention to the drying time and whether the glue is only or double sided. And work calmly and cleanly. Make sure that no glue gets on the hands. You will get it easier from that than from the inside of your heaven.
The flexible textile with a thin layer of foam is often for sale at clothing companies. But that is not cheap. Always buy a large excess, because the stuff must be applied without tension. Certainly in curves and corners.
In view of the optical importance of a clear sky, it is also not wrong to outsource the job to a professional.