The stretcher of your favorite canvas is damaged: with play between the wooden parts, traces of sawdust and insects? It is truly time to restore it! Don't stop there: paper and canvas may also need attention... Zoom: an activity at the limits of DIY.
Caution: before taking any action, carefully verify that it does not contain the mark of its original framer, in case it is valuable. It would be better to leave it to the care of a professional framer...
Fold the edges of the canvas over the stretcher bars, cut from a similar material. Attach with vinyl glue.
Make folds with the stretcher bars, pulling the canvas to give it the desired form. Position it temporarily with masking tape, then tack in place using pliers to hold the tacks.
Links
[1] https://www.cansonstudio.com/restoration
[2] //twitter.com/share?url=https://www.cansonstudio.com/print/676&text=Restore a stretcher in 3 steps https://www.cansonstudio.com/print/676 via @CansonPaper
[3] https://www.cansonstudio.com/printpdf/676
[4] https://www.cansonstudio.com/print/676
[5] https://www.cansonstudio.com/typology/basic-knowledge
[6] https://www.cansonstudio.com/restore-painted-work-4-steps