Sean P - couple things. Your apparent 682 shows on the list I have to be a 782. The first 3 digits are supposed to be the Kind Code. In your case 205 means it's a Cub Cadet Garden Tractor. The next 4 digits, in your case 0601 are to identify your Model. For IH built units until 6/81 and for the CCC built until 1984 the 0601 would be assigned to a Model 782. Since you say it's a 682 it may have been built after 1984 and I don't have production info for those years. Your actual serial number are the last 6 digits after the U. In your case 762843 is past those units built in 1984. So overall I don't know what model or actual unit you have. It would have been built by Cub Cadet Corporation, Cleveland, OH, which should be stated on the serial number tag on the side of your frame. You might find more info in the thread for CCC built units.
Sarah K - yup, lefty loosey, righty tighty is correct for the hydro relief valves.
Couple things:
1 - before you put the WD-40 on did you notice any fluid around one of the valves? If so you could have a faulty valve, not easily repaired but replaceable.
2 - do your valves have the little center buttons? If so and one is stuck down or part way down, that's also why you don't have reverse.
3 - if your valves do NOT have the little center buttons then you have the newer auto release style that came into production around the mid point of the Quiet Line tractors like your 1250.
4 - the valves are interchangable except you really need both to be the same style to operate correctly (both with the little buttons, or both withOUT the buttons).
5 - to verify a valve problem you can switch them side to side. Doing this should give you reverse but no forward drive IF your problem is one of these valves.
6 - there are lots of these valves available. New is pretty costly so I'd investigate getting a used one of the same style you have (button or no button) that looks good and clean, and if you can find out it was known to work at the time removed. You can try posting in the Wanted Section on here. I'll bet someone has a known good one available.
John B - you know, I gotta admit I like those colors. Very nice looking units you have there.