Maybe you could give us more info about you machine. Have you look to see if something has come off or come apart. Can you post some pictures so we can get a better understanding of what you talking about. Is your machine new, old, how many hours, is it hydro lift, is the fluid low, has a hose busted, maybe a stick or something has gotten jammed between the deck and frame.
On my 725, if I am adjusting the cutting height, the up/down switch works O.K. However, if I want to raise the whole deck to inspect or sharpen the blades, it is necessary to hit the DOWN button. keep holding the down button and when it has reached the lowest point, then the deck starts to raise. You also have to manually hold up the positive height adjustment lever while doing this. Not trying to insult your intelligence, but if you are new to the mower, this is necessary.
