Yes, you will need to take off the tiller to get the deck to go all the way down to the ground. Problem is there is a bar that goes from the rear lift mechanism that contols the deck lift. You can see it if you are looking at the rear of the tractor on the left upper arm that lifts the left part of the 3 pt hitch. The rototiller doesnt't allow the am to drop all the way so your deck stays up in the air a bit.
Just a heads up... I changed out the oil in the gear box on the deck and put in some Lucas 80 - 90 wt gear lube. Seems to run quieter. Super easy and cheap maintenance.