Fixing snags in looped carpets is a relatively easy job with the help of a nailset or small screwdriver and carpet seam sealer, available from home centers.

Count the number of curls along the pulled-out strand and make a single cut to allow the right number of loops for each side of the run. Outline the run with masking tape.

Apply the sealer/adhesive inside the run, and then, with the nailset or small screwdriver, press the portions of yarn that have old adhesive stuck to them back down into the backing, creating properly sized loops.