Before doing anything else set adjustment nuts on each side to the center and start again, with both centered check height then turn high side down one turn check both sides again, if more needed go to opposite side and turn up one turn, go back and fourth that will give you more adjustment than just one side.
Make sure tires are aired up to same amount, I run 10 lbs on rear and 12 lbs on front on most mowers.
You don't have to turn full turn each time when you get close turn a little each side.
The front of deck needs to be 1/4 to 1/2 inch lower than the back, that adjusts with bolt under nose of tractor.
If after a couple full turns each side and it's still out you need to look for bent hangers.
Look for scarred or chipped paint or twisting, check to see if each side looks the same.
You can take fender pan off just remember to hook wires back up for seat safety or mower won't start.