Make sure your tires are propery inflated.

Checked tires. They're ok.

Raise the rear of the deck by shorting the support chains, hooking in different links. Level by removing the deck cover and adjusting the linkage under there.

Walt Conner

I have the rear deck spacers on the wires at the highest level already.

What linkage allows me to adjust the forward deck height? I didn't see anything to adjust when I had the machine standing up.

Well you don't really have one of the "older machines" apparently.

Walt Conner

***"I have the rear deck spacers on the wires at the highest level already."***
Does that mean you have moved all the spacer ferrules to the bottom side of the rear lift arm?
Moving the ferrules from the top side of the lift arm to the bottom side will leave you with a taller cut of grass.
moving the ferrules to the top will get your grass cut shorter.
Just to make sure you are doing it the right way.

Yup, I have all the discs on the *bottom*.

Thank you for the explanation. Sounds like that could be my problem.

I've currently got a jerry-rigged system where I use a short piece of metal as a chock under the height adjustment lever so it is well beyond the top setting. That effectively raises the deck to a usable height.

However, should I be concerned that this will stress/break other parts?

I actually doubt your rig will add any more stress to the parts..........but I can't see what you are doing with that piece of metal (it's too far away from me).
If you are merely adding some thickness (shim) to the same point that normally carries the load of deck suspension I doubt you will suffer worse damage.