All glue sticks have sensitive, thin, plastic triggers. The trigger moves the glue stick forward as you need glue. Since this is a continual and manual procedure, the trigger gets a lot of wear. Being thin plastic, it cracks and breaks easily. You have to use the trigger carefully. Do not force the trigger. If you feel you have to force it, turn the gun off, wait for gun to cool down then restart it. I have notified manufacturers of this problem but heard nothing back. Make sure you keep any warranty info for return. This gun, so far, is doing great, but I am pampering it and would love a gun that would work faster, longer, and with more glue. Please glue gun manufacturers, make the trigger "metal"! Otherwise, this gun heats quickly, dispenses smoothly, seems to heat longer, and comes with a battery that also serves as a sturdy base when not in use. The battery also makes it cordless which, for me, is an absolute necessity. I love that this gun uses full size diameter sticks and 40 were included.