I use hot-melt glue to make temporary part connections (such as attaching templates to workpieces). But invariably, the glue stick in the gun is nearly spent when I need it, to the point that the gun’s receiver won’t advance it anymore.
Here’s my fix: heat the gun up and push out a bit more glue with a dowel or pencil. Then use that glue to attach a new stick to the old one. This enables the receiver to start feeding the new stick into the gun when the old one is completely gone. It also wastes less glue.