In high winds, the loads imparted to the sheets can be enough to cause a drum to unfurl if the furling line lets go or chafes through. Particularly so if they flog about. Most drums have one or more holes at the base that allow one to drop a locking pin or bolt through (tie a strip of red spinnaker cloth to the top of the bolt to remind oneself it is in place). Short of that, pulling the sheets forward and tiying them to the bottom of the sail with a couple of wraps of a sail tie will keep things tidy.
FWIW...
PS: We have used Sailcare but for simply sewing up a couple of seams and repairing a UV cover, the local North loft is sufficient and a heck of a lot faster!
