Thread the new elastic through the buckle loop.

Position the buckle loop at the end of the elastic, with just enough excess strap to bend over and sew in place.

Use a straight stitch on the sewing machine to sew the folded part of the elastic back onto itself, keeping the buckle loop fastened in location. Repeat this 2-3 times to give several rows of stitching for extra strength. Use a locking stitch at the beginning and end.

Tip: if your sewing machine has enough power, fold the end of the elastic twice, before stitching. This will result in a neater end, with less chance of fraying.