If it is coming out around the shift lever(s), you have a clogged vent pipe.
Look under the seat (left hand when sitting on tractor seat) near the top of the transmission case. You should see a small tube (pipe) that sticks out horizontally towards the rear fender. It looks sort of like a question mark shape but laying down instead of vertical. The starting point of the question mark should be the open end of the tube.
Often the tube will get plugged by bugs or their nests. There is a nut that can be unscrewed and the tube will come off and you can clean it out with a wire or pipe cleaner and re-install it. Problem should be solved.
Some people tie something (screen, sock…) over the vent opening to keep the bugs out if it is a recurring issue.