Deck height problem

I have a 2016 X584 48" deck with a powerflow which I mulch and bag in the summer and push and blow in the winter. I have no problem leveling the deck when I mulch but when I install the powerflow and try to level the deck I run out of threads when I try to raise the right side of the deck. The tires are set to 12psi in rear and 12 psi in the front plus I also tried 10 in the rear which didn't change anything. If I raise the pressures to high the ride is awful. The height bolts are hard to move unless I put a 2x4 under the deck to take the pressure off. This is the first year that I've had this issue and I'm the only one who uses this machine. Could the rocker shaft be worn out where the screw goes threw? I have striped out 2 adjusting wrenches and I'm perplexed. I bought this machine new and this is the first big issue I have had. I know how to adjust the deck because I have been doing it for 6 years with no issues. No broken rocker shaft springs that I can see either.