Kenmore 70 Series: water doesnt stop filling, just drains out?

I have a Kenmore 70 series washer. Everything works great except when it is filling with water, it doesnt ever stop filling. But if I advance timer, it begins and runs just fine--goes through all cycles, spins, etc.

Is there some kind of float (like a toilet) that is supposed to shut the water off after reaching a certain fill point? I'm pretty handy and wouldnt mind tackling the job, but i don't know how the water level sensor works. is it electronic? Mechanical? Any advice would be helpful esp. if you know where I can find a cut away diagram/schematic that shows washer components.

Hey just did a little experimentation and this is what we found: Try raising the height of the drain hose. We have a plastic drain hose (similar to a vaccuum cleaner hose) with a rubber "U" pipe at the end of it. We emptied the tub, set it to "high" and let it fill up. Sure enough it wouldn't cut off it filled and then kept running out the drain hose. I grabbed the "U" pipe and raised it up just past my waist height and it shut off and went into the next cycle!!

WOOOO HOOOO just saved a couple hundred buck!