Just restoring the brake calipers on one of my old bikes and come up with the old problem of frozen bleed nipples that haven't been touched for years. My old dad showed me how he released them without them snapping off. Get the whole nipple area very hot then cool the nipple only down with iced water on a rag, works every time for me. Many of you will probably know this method, but may be useful to those that don't.