Hey Barbara,
There are a couple of things you can do. To repair a small loose loop you can follow this guide: [guide|19434]
If you need to resew a line of stitching you can follow this guide: [guide|19435]
If you have a table on your sewing machine (a plate that attaches) you may need to remove it to slide the sleeve into the sewing machine.
I hope these guides help you. If not, you can contact Patagonia customer service for further help.
Good luck and let us know how it goes!