Belt ~ Why is this so complicated?? No manual

Question

We just recently moved and I can't find my user guide anywhere. It's been awhile since I've used this vacuum and I can't remember if the belt needs to be hooked up or not when running the regular floor mode. I left it unhooked and the suction doesn't seem to work that well and I'm scared to burn up my belt. So I either have a suction problem or a belt problem.... ;-)
Thanks!