If you push the joystick all the way forward you should feel it go into float and the handle should stay up on it's own. If you pick the front of the tractor up a little with the loader, it should fall if float is working.
I'll just add that you might have to do it with a quick pop flick of the wrist. that's how it works in JD. a slow push might not get it into the detent. it just a feel kind of thing.