STX38 (yellow deck) - Uneven Deck

The Problem: my mower deck on my STX38 (yellow deck) is very uneven. I've included pictures below to illustrate the severity, but the deck is so uneven that the right side's guide wheel is actually not touching the ground, and it's (obviously) causing a very uneven mow pattern in my lawn. Also it should be noted that the blade height adjustment bar is also uneven (pictured below). This was actually the first thing I noticed - last time I mowed, I went to raise the height of the deck, and the bar didn't click on both sides together.

What I've tried to so far: I purchased a John Deere leveling gauge, and I've tried performing a basic leveling, by adjusting the three nuts attached around the left, rear wheel well (pictured below). However, this didn't seem to make a dent in the level of the deck at all.

My guess: I'm assuming something is loose at this point, although I can't tell what. I have a manual, but I'm definitely no expert with John Deere mowers, or this kind of thing in general. I'm just a vaguely handy guy (thanks Dad <3). The main reason I think something is loose, is that I can actually press down on the right side of the deck and it seems to spring back up a bit.

Thanks in advance for any help. I've tried to find an answer to this question before posting it, but feel free to point me to another post if this has already been solved.

have you checked tire pressures?

have you checked tire pressures? how are your measurements left vs. right?

I would start by removing the deck and check to see why the height adjusting lever is not moving the same. After you get that problem solved you can go about leveling the deck. The adjuster you have pictured is for side to side and you should have another in the front of of the tractor for front to back adjustment. Which you have it off check to make sure nothing is broke or loose on the tractor or lift mechanism.

Thanks guys! I have checked the tire pressure and evened it all up. It was a bit uneven initially, but this didn't really put a dent into my problem.

@Rivets I will definitely take your advice and get to removing the deck as soon as I have the time. If I can figure it out, I'll let you guys know what I came up with, and if I run into a dead end, I'll post some pictures of what I find and we'll go from there.

Thanks again y'all!

Also I think I'm going to take the time to clean the thing up a bit while I take it apart!

The lift rods and shafts flog out oval after a while and your mower ain't no spring chicken.
JD have all of their parts diagrams on line
So find your deck and print out the left mechanism so you can compare what you have to what should be there.

@bertsmobile1 - thank you for the specific tip. I'll make sure to use that to find the info I need. Thanks again, gentlemen. Will report back soon.

I buy high tensile washers by the box full and am always welding them over flogged out holes.
HT washers are 2 to 3 times thicker than standard ones & made from a stronger grade of steel heat treated to be harder.
Rods & shafts are usually replacable but the bits with the holes in them are usually not.
JD also use a lot of replacable plastic bushes.