The deck tilts down forward so the guide wheels are always in contact with the ground. how can i level the deck so it raises and lowers equally front and rear?

level the deck off as a tilted deck will cut lower on the low side
adjust the deck mounting bars or deck pilot wheels
check that the cutter/pulley spindles are in good condition and not falling down

first check that the blade or mandrel is not bent or damaged --and check the air pressure in tires on right side --lower deck towards ground on a level surface until left makes contact now adjust the level arms they are on either side of cutter till right side is level with left on some of the older decks can adjust the front deck wheels also

if its a garden tractor then you will first need to remove the mowing deck , this is easy if you have something to run front wheels up on to allow you room to pull deck out the side ,set deck height all the way down, save the drive belt . save the deck pins . locate the front chassis mounting arms and drive up to blower allow rear mounting arms to go between the two front wheels till the back of blower meets the front of chassis mounting arms (tight fit) install pins at all four points of contact , install belt to blower and front pto of machine (install any guards for belt) then raise blower from ground with deck height adjustment lever (it might feel heavier) test it to prove good contact your done
if its a three point (this is the reason I own one know) you back up to blower lower the mounting arms , engage the quick pins , install the drive shaft between the blower and machine with a quick spring snap , connect top link to tractor get back in seat and start machine raise three point an go !!

1) NEVER adjust to where the deck wheels touch the ground. The wheels are to ride 1/4" off the ground. 2) The long lever to your left which raises & lowers the deck has 3 settings. 1- Fully back toward you which has the deck raised (called transport mode). 2- Halfway down which is the normal mowing mode (called float mode) 3- Fully away from you which sets the deck fully on the ground. This mode is ONLY used for VERY rough terrain where the deck risks getting pushed into "transport" or "full up" mode & getting stuck there. 3) On front-to-back tilt, the front should be 1/2inch lower than the back for least damage to the grass. Ok-now to adjust "cutting" height. 1) Park on a level, flat surface. 2) Pull the deck lever fully back toward you to put the deck into "transport" mode. 3) twist the "cutting" height knob (just below your seat) to the height you want the grass cut. Has choices by 1/2" increments from 1" to 3.5". The deck in "transport" mode is 4". 4) Lower the deck lever to the midway/"floating" mode point. 5) Adjust each deck wheel with its own peg & pin to have at least 1/4" clearance from ground. Thats it for "cutting height" adjustments
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call your deere dealer,
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Troubleshooting

Service Mower

cant find info for you,call dealer

Leave aside all the puffery about 3-1 and such, you described a front wheel drive (pull) walk-behind (FWD), but are asking why the rear wheels won't propel. When you push down the hand grip the front wheels should spin free. Whan you lower from wheels by releasing pressure on hand grips, turning wheels lowered to ground should propel the mower along with its unpowered rear wheels now turning be ground contact. Reminder, never, ever lift rear drive wheels of any mower off the ground while walking behind with engine running:

1. You could be struck by blade propelled object.
2. You could pull mower and spinning blade backward onto your feet.
3. You could lose balance and be pulled forward in a fall.

Contemporary FWD mowers are recognized by a black chain housing on deck top leading from engine to left front of deck. RWD propelling chains are situated underneath deck so cannot be seen from above.

there should be adjustments on each wheel.
Place the machine on a flat level surface and adjust each wheel so the blades are at the height you want it to be. Make sure all the wheels are all at the same height. Usually, the bottom of the deck lip to the floor equal all around.

I've had to do this at least 5 times. If you look under the body, there are two supports that carry the mower deck and lift and lower it. Each of these has a nut that holds up the deck and the nut is on a stud that goes up and down when you raise or lower the lever. Put the deck in the middle of it's range, around #3, make sure the key is off, move your blades so they are on the right and left edge of the deck.
Get yourself a device to measure blade to ground height, I have a block of wood that is 3 inches long. Make sure your floor or ground is level and tires are properly pumped up. Then raise or lower the adjustment nuts until both sides are equal height.

Gary

Move machine to flat/level surface,with deck raised put a 2x4 between rear of deck and ground.Make sure that the 2x4 goes all the way under deck from one side too the other.Once that is done lower deck all the way and make sure lift lever is all the way forward.Then on the rear top side of deck loosen bolt that holds arm to deck bracket,pull bracket as far down as you can then retighten bolt.This is also the point where you can level deck side to side.

Park the tractor on a firm, level surface. . .
At the lower end of the lift/lower travel slot, there should be a plastic cover which you pop up so that your blade lift handle goes all the way down (it should say something about blade level on there somewhere. . . . .
After you have the handle in this position, look at the front lift arms of the mower deck and find the 2 large wing nuts, one on each side. . . . .
Loosen these while the deck is down and then retighten them Your deck is now level and will lift to its highest recommended position when you raise the lever

There should be two threaded rods with a nut on them that goes from the frame to the deck. Check the height of each blade and which ever side is out of balance you can disconnect that sides rod (usually held onto the mount with a clip or cotter pin) and turn the rod to either raise or lower your deck until it is level.

The above was for leveling your deck.

If you just need to raise or lower the deck depends on if you have a lever on the right side with a push button on top just depress the push button and push forward to lower or pull back to raise.
It might have a round knob that you turn to raise or lower.

Good luck