Sounds like the same problem as with sheared pin on brushhog shaft.
Assuming you can get to the pin location, use a bright flashlight looking at the through-hole. I'll bet you can see the dutchman pin go by as you roll the inner shaft around. Then get a drift and plenty of hammer and drive it out the far side. You may have to wiggle the two pieces to get the holes to align even after you see where it is.
Lordy I hope you don't have a tapered or watermelon pin. I've had to drill them out. Go back with a soft 'no grade' (actually Gr-2; no head markings) bolt long enough that threads are not exposed to rotational force. I use a NyLock nut to keep it together. Cut off excess bolt length if you'll be reaching into the area around the pin. Even then be careful.