Hi Prosperity:
Not sure if this will be of any help to you, but this is what I have encountered with the 62" MMM on my 2210 that I have had now for about a week. Got the unit with the FEL, MMM and Herd spreader. Removed the FEL and spreader to do some mowing. Thought the MMM was in the locked position, but I could not get it unlocked. Could not raise or lower the MMM and could not move the height adjustment knob. The knob was set on the 5" mowing height setting according to the MMM adjustment knob decal. Based on this cutting height setting, I believed the MMM was not "locked" in place, rather, it was stuck in the up position.
The dealer salesman and mechanic came to the house and both had to lift the MMM up and down and it finally became unstuck, if that's what you want to call it. Here is what the mechanic finally found. The MMM could go all the way down, but not all the way up to the point it would lock in as it is designed to do. You could only turn the dial up to the 4" setting on the decal. What he then found, and I hope I can explain this so it's understandable, is that the "L" shaped piece of metal that the 3 point hitch arm engages to raise and lower the mower was factory made defective in that the angle of the "L" was not great enough to lift the MMM high enough so it could be locked in place. They have ordered a whole new "kit", not just the defective "L" shaped piece of metal. I don't know what the kit entails but I should find out soon.
Sorry for being so long winded, but I wanted to mention this in the event others might encounter it. Once this repair is completed, I am going to address the proper location of the adjusting knob decal, adjusting the MMM to the adjusting knob decal settings and the respective cutting heights. I'll let everyone know how that turns out.
Chuck