Rope locked on B&S Craftsman Push Mower Model#917.388834?

My grass is rather thick in my backyard,so my mower has stalled a few times when I mow the back yard,but when I lift it up it would do ok,because grass comes out from under it.It's a 4.5 B&S Craftsman rotary push mower that I bought about the middle of last summer.I do keep the bottom of the mower cleaned out.
Well, this evening it died on me and the pull rope will barely move and when I moved the blade it made a squeeking noise.I don't want to force the pull rope for fear of breaking it.
Knowing my luck it's something expensive to fix.
I hope I gave enough info.