New BX 23 to replace to 2200?
I did the same thing. You will be glad you did.
If this is first install of MMM, should be perfect from the dealer.
Suggest you get your dealer to properly adjust and level the mower deck.
The black handle simply pulls off. It will only fit one way.
There are no adjustments to the selector knob.
Being off by 2 inches sounds like something is wrong. You cannot adjust 2 inches in the lift arms. Is something catching or binding with the selector knob, MMM or 3 point hitch arms?
Try to raise the mower completely, then turn the dial to the 3 position. Now lower the mower til it stops and take your measurements. If you make any adjustments to the lift arms, be sure to level the deck by adjusting the front attachment as well. Ideally, the front tip blade should be 1/4 inch lower than the rear tips of side blades.
Off by 2 inches sounds like something more than an adjustment to me.