Hello, I have a 2001 M9000DT. The dust seal that goes around the shift stick has a rip in it. When i am operate the tractor on steep terrain, (pond bank. etc) Transmission oil comes leaking out of the rip. When i am on anything remotley level, this dosen't happen. Do I need to replace the rubber dust seal only? Or would i need to replace the metal sealing unit that is pressed into the transmission? Thanks for your help!