figure this out yet? I'm having the exact same issue, not tilting left. I use to be able to adjust it by doing the procedure with the block on the right side of the c frame. But doesnt work now. I can do pretty much as you have, but instead of come along I will set the left bottom corner of the blade on a block or something, then tilt blade left, it will suck the left angle cylinder in most the way. But as soon as you go to use it, it goes right back to where it was.
Really aggravating trying to grade without being able to tilt it left also.
Not sure why it quit being able to be adjusted using that block, unless something inside the block is leaking past whatever goes on in there!