This tip is not mine but that of Treeditions . I stumbled across it on Facebook and discovered that they regularly post handy tips for weavers.
There are a couple reasons you might use this. A broken warp thread or a knot in the warp needs to be sorted out. It involves a replacement thread being put in place and hung over the back beam. The problem is keeping the tension on it and also stopping it unravelling or getting tangled elsewhere.
This tip involves winding the thread onto a cone and then covering it with another cone. It won't come undone, it won't tangle, it's easy to lengthen when you need to and basically, it's just brilliant!
Give it a go when you next meet a knot or have a broken thread.