Craftsman Dremel won't spin?

I borrowed a Craftsman drememl from a friend, so it's not mine. I can't get the cutting disk to turn now. It worked for 5 min. Then I played with the release button for the head to change to a sanding attachment and it didn't spin anymore. There's still power. If I push it around it starts to go but when any presure is applied to the tool it just stops. Like it's not catching. What do I do? Did I brake it or is there something easy that I'm doing wrong.