Dartman said:I might add that if he used 3M-76 it won't hold stretched cloth very well.
76, 77 and 90 all come in a black can so you'd need to check the number on the can.
If not using a roll-on glue then 3M-Super77 is the weapon of choice - get it at Home Depot for around $10 in the paint department.
If you're up to trying to fix this - pull the rails off, lift up the slate on both ends and slide a 2X4 underneath each end.
You'll need a helper for this.
Rework the pocket area(s) by undoing the cloth, reglue and restretch.
Spray glue is applied to the slate edge and the cloth (where it will hit the edge when stretched.
Allow 3-4 minutes for the glue to dry before applying. IOW - read the directions on the can.
Lay some newspapers or cardboard on the cloth to prevent overspray on the playing surface.
You may have to rework the pocket cuts slightly and if so then pull on the cloth and not the cut strips.
I used 76 for years and it's holds as good as the others.