OK
I had tons of troubble untill recently, after watching Jordan nose manny the Box I decided to learn them propley...
1. MAKE SURE THAT YOU ARE LEANING FOWRD
when I say this its increadably odvious but; If you dont hold fowrds while mannying you jest wont be able to keep it. So make sure your groin is close to the bars when your nose manualing.
2. It sometimes helps to put 2 sticks down and graducally move them further and further apart.
3. Commit... Ive never aten shit on a nose manually before, and ive been going fast and hit potholes, stones you name it Ive hit it... Even a car haha...
4. Just practise.. alot.